- Email: [email protected]
Disparities in the treatment of colon cancer in octogenarians
The American Journal of Surgery (2009) 197, 624 – 628
The North Pacific Surgical Association
Disparities in the treatment of colon cancer in octogenarians Karin M. Hardiman, M.D., Ph.D.*, Molly Cone, M.D., Brett C. Sheppard, M.D., Daniel O. Herzig, M.D. Department of Surgery, Oregon Health & Science University, Portlan, OR, USA KEYWORDS: Colon cancer; Chemotherapy; Disparities; Octogenarians; Elderly
Abstract BACKGROUND: Disparities in healthcare for the elderly are understudied, despite the increasing proportion of patients over 80 years of age. Advanced age is a principal risk factor for colorectal adenocarcinoma, but there are few data to guide treatment in the elderly patient population. METHODS: We performed a retrospective review of prospectively gathered data on 10,433 patients diagnosed with primary colon tumors between 1998 and 2004. We compared demographics, stage at diagnosis, and initial treatment between patients younger than 80 years and those age 80 years or older. RESULTS: Patients who were ⱖ80 years old made up 30% of the database. Older patients were less likely to have colectomy for advanced or metastatic disease than younger patients. Patients who were ⱖ80 years of age had fewer lymph nodes removed than younger patients (11 vs 10, P ⬍.01). Older patients were significantly less likely to receive chemotherapy for every stage of colon cancer than younger patients. When older patients did get chemotherapy, it was more likely to be with a single agent. Multivariate analysis revealed that predictors of receiving chemotherapy for patients ⱖ80 years of age include living in an urban county, younger age, and worse stage at diagnosis. CONCLUSIONS: Older patients make up a large portion of the patients treated for colon cancer and are treated less aggressively. While some of the treatment difference may be explained by medical factors, demographic factors affect treatment decisions as well. © 2009 Elsevier Inc. All rights reserved.
The elderly population is one of the fastest growing groups in the Unites States. The percentage of the population that is ⬎80 years old grew 14% between 1990 and 2000.1 Life expectancy is also rising: the average 80-year-old is expected to live 8.9 years; for an 85-year-old it is 6.6 years and for a 90-year-old it is 4.8 years.2 These factors have recently stimSupported by the Oregon Clinical and Translational Research Institute (OCTRI), grant number UL1 RR024140 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. * Corresponding author. Tel.: ⫹1-503 494 4373; fax: ⫹1-503 494 8884. E-mail address: [email protected] Manuscript received November 7, 2008; revised manuscript December 22, 2008
0002-9610/$ - see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.amjsurg.2008.12.018
ulated more research of this group, but healthcare decisions for elderly patients are still understudied.3,4 In particular, much of the data guiding the treatment of colorectal cancer was obtained in studies that excluded elderly patients. The result has been a wide variation in treatment, especially for the growing group of patients over 80 years old. Some of this discrepancy is based on the uncertain benefit in this population, since elderly patients are often excluded from randomized controlled trials. The Multicenter International Study of Oxaliplatin/5-Fluorouracil, Leucovorin in the Adjuvant Treatment of Colon Cancer (MOSAIC) trial, which is widely cited to provide the basis for first-line chemotherapy in colon cancer, only included patients up to age 75.5
K.M. Hardiman et al.
Treatment of colon cancer in octogenarians
Table 1 Demographics and tumor characteristics: patients age ⱖ80 years were significantly more likely to be female and live in an urban area than younger patients
Age (median, [IQR]) Percent female Percent living in rural county Percent of total patients in database Percent proximal tumors Percent with positive lymph nodes
Age ⱕ79 years
Age ⱖ80 years
68 (59–74) 48 35 70.5
84 (82–87)* 58* 31* 29.5
47.8 40
59.5* 32*
*P ⬍ .05.
In addition, adjuvant chemotherapy is inconsistently used in the elderly, despite having well-documented survival benefits in the general population for node-positive disease.6 This survival benefit is also shown in retrospective studies of elderly patients: Jessup et al showed a 19% improvement in 5 year survival for patients ⱖ80 years of age who received chemotherapy, when compared to others in their age group.7 Disparities based on age, in colorectal cancer diagnosis and treatment, are poorly understood. The purpose of our study was to examine the treatment of patients ⱖ80 years old with colon cancer using a large state cancer database to determine the cause and nature of disparities in care.
625
Review Board both approved this study. OSCaR provided de-identified data on demographics, stage, and initial therapy for 10,433 patients with primary colon tumors diagnosed from 1998 through 2004. These data were entered into SPSS 15.0 (SPSS Inc., Chicago, IL). The age at diagnosis was used to categorize the patients into being 80 and older or 79 and younger. Rural and urban designations were based on the Oregon Office of Rural Health definitions. OSCaR reported tumor staging according to the Surveillance, Epidemiology and End Results (SEER) staging system.
Statistics We used SPSS for all statistics. We compared patients who were 80 and older to patients who were 79 and younger at the time of diagnosis. Categorical variables were compared with the chi-square test, and continuous variables with Student t test or Mann–Whitney U test, as appropriate. Logistic regression modeling was used to assess the use of chemotherapy.
Results Demographics Of the 10,433 patients, 7,354 (70.5%) were ⱕ79 and 3,789 (29.5%) were ⱖ80 years old. Patients ⱖ80 years of age were more likely to be female and less likely to live in a rural county than the younger patients (Table 1).
Methods
Tumor characteristics and stage at diagnosis
Database
Older patients were less likely to have stages in situ, regional to lymph node direct extension, or distant metastatic disease at presentation, but they were more likely than younger patients to have disease that was regional by direct
The Oregon Health & Science University Institution Review Board and the Oregon State Cancer Registry (OSCaR)
Figure 1 Stage at diagnosis. Reg by Dir Ext ⫽ regional by direct extension; Reg to LN’s ⫽ regional to lymph nodes; Reg to LN ⫹ DE ⫽ regional to lymph nodes and direct extension; Distant Mets ⫽ distant metastasis.
626
The American Journal of Surgery, Vol 197, No 5, May 2009
extension or unknown stage (Figure 1). Tumors in patients ⱖ80 years of age were more likely to be proximal to the splenic flexure (59.5 vs 47.8, P ⬍.001). And, older patients had positive lymph nodes in 32% of the specimens removed versus 40% for younger patients (P ⬍.001) (Table 1).
disease (Figure 3A). When chemotherapy was given to patients ⱖ80 years of age, they were significantly less likely to receive multi-agent chemotherapy (Figure 3B). Multivariate logistic regression analysis of predictors of receiving chemotherapy for each of the 2 age groups was performed. Predictors of receiving chemotherapy were different for patients ⱖ80 than for patients who were 79 or younger. Predictors in older patients included increased age, worse stage of disease, and living in an urban environment, but predictors in younger patients were worse stage and having fewer lymph nodes removed. Year of diagnosis and sex of the patient were not predictive of receiving chemotherapy in either age group.
Treatment Patients who were ⱖ80 years old were less likely to have surgery if the stage was regional by direct extension, distant metastasis, or unknown, but they were just as likely to have surgery for any other stage as younger patients (Figure 2A). Patients ⱖ 80 years old had significantly fewer lymph nodes retrieved at surgery (10 vs 11, P ⬍.05). However, when the data were split according to year of diagnosis, only 2,004 had a significant difference in lymph node retrieval (11 vs 14, P ⫽ .001) (Figure 2B). Chemotherapy was given to patients ⱖ80 years old significantly less often than younger patients for every stage of
Comments The US population is becoming increasingly older, but data on how best to care for these patients are sparse. The
Figure 2 (A) Stage at diagnosis vs percentage of patients having a colectomy. Reg by Dir Ext ⫽ regional by direct extension; Reg to LN’s ⫽ regional to lymph nodes; Reg to LN ⫹ DE ⫽ regional to lymph nodes and direct extension; Distant Mets ⫽ distant metastasis. (B) Number of lymph nodes vs year at diagnosis.
K.M. Hardiman et al.
Treatment of colon cancer in octogenarians
627
Figure 3 (A) Percentage of patients receiving chemotherapy for each stage. Reg by Dir Ext ⫽ regional by direct extension; Reg to LN’s ⫽ regional to lymph nodes; Reg to LN ⫹ DE ⫽ regional to lymph nodes and direct extension; Distant Mets ⫽ distant metastasis. (B) Type of chemotherapy given.
purpose of this study was to examine disparities in treatment of colon cancer related to age using a large state database. Unfortunately, much of the key research guiding our current standard of care for diseases such as colon cancer has not included those over 80 years of age. This may in part be due to the ever-changing definition of “elderly.” In our study, about a third of Oregon’s population with colon cancer was age 80 or older. Their disease did not have the same stage distribution as in the younger patients, but this was likely due to the number of patients whose stage was unknown. The treatment of the patients age 80 and older was different from that of their younger counterparts. This agrees with prior smaller studies such as that reported by Mahoney et al, who showed that 34% of patients age 80 or older are not even offered chemotherapy.8 While medical comorbidities might preclude its use in some patients, what is concerning is how little chemotherapy these older patients are receiving. The limited data available do indicate that older patients benefit from receiving chemotherapy, and that age does not diminish the increase in survival derived from the chemotherapy.7,9 This area clearly warrants further study to help delineate which
patients will benefit from chemotherapy, to what degree, and at what cost. With respect to surgical therapy, our study shows that patients age 80 or older were less likely to have a colectomy for advanced or metastatic disease, but they were just as likely to undergo a colectomy for local disease when compared to younger patients. This is consistent with other studies showing an excellent rate of surgical intervention for colorectal cancer among patients age 80 or older.10 The morbidity of colectomy, or even metastatectomy, is favorable in well-selected elderly patients. Mazzoni et al showed in a small study that even liver resection for colorectal metastasis is justified for selected patients over 70 years old.11 While many elderly patients in our study did have surgical treatment of their cancer, fewer lymph nodes were resected from older patients. This may be due to surgical factors, such as less extensive resections, or patient factors, such as smaller or fewer nodes in the elderly.12 The less extensive lymph node evaluation may have led to understaging of the elderly patients in this study, as there were fewer patients with positive nodes among the elderly pa-
628
The American Journal of Surgery, Vol 197, No 5, May 2009
tients. The evaluation of an adequate number of lymph nodes may be an important quality marker in the elderly. Bilimoria et al recently showed that the improved survival benefit derived from examination of 12 or more lymph nodes was present in all age groups including patients age 78 and older.13 A weakness of this study was its retrospective design using only a database for information. This database did not report patient comorbidities that would have played a role in the decision for treatment. The database lacked information regarding treatments offered but not received, which could significantly affect the number of patients ⱖ80 years of age receiving chemotherapy and/or surgery. Mortality and recurrence of disease were also absent. In summary, nearly one third of colon cancers in Oregon are diagnosed in patients ⱖ80 years old. Treatment of these patients appears to be different based on age. In the growing elderly population, there are few well-conducted trials and ill-defined guidelines, which may result in differences in treatment. The average 80-year-old person is expected to survive ⬎5 years, and it is unclear whether the differences in treatment of elderly patients are justified. More research into the proper care of those 80 and older would help to establish consistent guidelines for colon cancer treatment.
References
Acknowledgment The authors would like to acknowledge the hard work of the staff of the Oregon State Cancer Registry, Oregon Department of Human Services, Portland, OR.
1. CensusScope, population pyramid and age distribution statistics. University of Michigan. Available from: http://www.censusscope.org/us/ chart_age.html. Accessed November 1, 2008. 2. Arias E. US Life Tables, 2003. United States Department of Health and Human Services, Centers for Disease Control and Prevention; 2006 April 19. Report No. 54. 3. Trimble E, Carter C, Cain D, et al. Representation of older patients in cancer treatment trials. Cancer 1994;1:2208 –14. 4. Murthy VH, Krumholz HM, Gross CP. Participation in cancer clinical trials: race-, sex-, and age-based disparitie. JAMA 2004;291:2720 – 6. 5. Andre T, Boni C, Mounedji-Boudiaf L, et al. Oxaliplatin, fluorouracil, and leucovorin as adjuvant treatment for colon cancer. N Engl J Med 2004;350:2343–51. 6. Sundararajan V, Grann VR, Jacobson JS, et al. Variations in the use of adjuvant chemotherapy for node-positive colon cancer in the elderly: a population-based study. Cancer 2001;7:213– 8. 7. Jessup JM, Stewart A, Greene FL, et al. Adjuvant chemotherapy for stage III colon cancer: implications of race/ethnicity, age, and differentiation. JAMA 2005;294:2703–11. 8. Mahoney T, Kuo Y, Topilow A, et al. Stage III colon cancers: why adjuvant chemotherapy is not offered to elderly patients. Arch Surg 2000;135:182–5. 9. Iwashyna TJ, Lamont EB. Effectiveness of adjuvant fluorouracil in clinical practice: a population-based cohort study of elderly patients with stage III colon cancer. J Clin Oncol 2002;20:3992– 8. 10. O’Connell J, Maggard M, Ko C. Cancer-directed surgery for localized disease: decreased use in the elderly. Ann Surg Oncol 2004;11:962–9. 11. Mazzoni G, Tocchi A, Miccini M, et al. Surgical treatment of liver metastases from colorectal cancer in elderly patients. Int J Colorectal Dis 2007;22:77– 83. 12. Lemmens V, Lijnschoten I, Janssen-Heijnen M, et al. Pathology practice patterns affect lymph node evaluation and outcome of colon cancer: a population-based study. Ann Oncol 2006;17:1803–9. 13. Bilimoria KY, Stewart AK, Palis BE, et al. Adequacy and importance of lymph node evaluation for colon cancer in the elderly. J Am Coll Surg 2008;206:247–54.
The North Pacific Surgical Association
Disparities in the treatment of colon cancer in octogenarians Karin M. Hardiman, M.D., Ph.D.*, Molly Cone, M.D., Brett C. Sheppard, M.D., Daniel O. Herzig, M.D. Department of Surgery, Oregon Health & Science University, Portlan, OR, USA KEYWORDS: Colon cancer; Chemotherapy; Disparities; Octogenarians; Elderly
Abstract BACKGROUND: Disparities in healthcare for the elderly are understudied, despite the increasing proportion of patients over 80 years of age. Advanced age is a principal risk factor for colorectal adenocarcinoma, but there are few data to guide treatment in the elderly patient population. METHODS: We performed a retrospective review of prospectively gathered data on 10,433 patients diagnosed with primary colon tumors between 1998 and 2004. We compared demographics, stage at diagnosis, and initial treatment between patients younger than 80 years and those age 80 years or older. RESULTS: Patients who were ⱖ80 years old made up 30% of the database. Older patients were less likely to have colectomy for advanced or metastatic disease than younger patients. Patients who were ⱖ80 years of age had fewer lymph nodes removed than younger patients (11 vs 10, P ⬍.01). Older patients were significantly less likely to receive chemotherapy for every stage of colon cancer than younger patients. When older patients did get chemotherapy, it was more likely to be with a single agent. Multivariate analysis revealed that predictors of receiving chemotherapy for patients ⱖ80 years of age include living in an urban county, younger age, and worse stage at diagnosis. CONCLUSIONS: Older patients make up a large portion of the patients treated for colon cancer and are treated less aggressively. While some of the treatment difference may be explained by medical factors, demographic factors affect treatment decisions as well. © 2009 Elsevier Inc. All rights reserved.
The elderly population is one of the fastest growing groups in the Unites States. The percentage of the population that is ⬎80 years old grew 14% between 1990 and 2000.1 Life expectancy is also rising: the average 80-year-old is expected to live 8.9 years; for an 85-year-old it is 6.6 years and for a 90-year-old it is 4.8 years.2 These factors have recently stimSupported by the Oregon Clinical and Translational Research Institute (OCTRI), grant number UL1 RR024140 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. * Corresponding author. Tel.: ⫹1-503 494 4373; fax: ⫹1-503 494 8884. E-mail address: [email protected] Manuscript received November 7, 2008; revised manuscript December 22, 2008
0002-9610/$ - see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.amjsurg.2008.12.018
ulated more research of this group, but healthcare decisions for elderly patients are still understudied.3,4 In particular, much of the data guiding the treatment of colorectal cancer was obtained in studies that excluded elderly patients. The result has been a wide variation in treatment, especially for the growing group of patients over 80 years old. Some of this discrepancy is based on the uncertain benefit in this population, since elderly patients are often excluded from randomized controlled trials. The Multicenter International Study of Oxaliplatin/5-Fluorouracil, Leucovorin in the Adjuvant Treatment of Colon Cancer (MOSAIC) trial, which is widely cited to provide the basis for first-line chemotherapy in colon cancer, only included patients up to age 75.5
K.M. Hardiman et al.
Treatment of colon cancer in octogenarians
Table 1 Demographics and tumor characteristics: patients age ⱖ80 years were significantly more likely to be female and live in an urban area than younger patients
Age (median, [IQR]) Percent female Percent living in rural county Percent of total patients in database Percent proximal tumors Percent with positive lymph nodes
Age ⱕ79 years
Age ⱖ80 years
68 (59–74) 48 35 70.5
84 (82–87)* 58* 31* 29.5
47.8 40
59.5* 32*
*P ⬍ .05.
In addition, adjuvant chemotherapy is inconsistently used in the elderly, despite having well-documented survival benefits in the general population for node-positive disease.6 This survival benefit is also shown in retrospective studies of elderly patients: Jessup et al showed a 19% improvement in 5 year survival for patients ⱖ80 years of age who received chemotherapy, when compared to others in their age group.7 Disparities based on age, in colorectal cancer diagnosis and treatment, are poorly understood. The purpose of our study was to examine the treatment of patients ⱖ80 years old with colon cancer using a large state cancer database to determine the cause and nature of disparities in care.
625
Review Board both approved this study. OSCaR provided de-identified data on demographics, stage, and initial therapy for 10,433 patients with primary colon tumors diagnosed from 1998 through 2004. These data were entered into SPSS 15.0 (SPSS Inc., Chicago, IL). The age at diagnosis was used to categorize the patients into being 80 and older or 79 and younger. Rural and urban designations were based on the Oregon Office of Rural Health definitions. OSCaR reported tumor staging according to the Surveillance, Epidemiology and End Results (SEER) staging system.
Statistics We used SPSS for all statistics. We compared patients who were 80 and older to patients who were 79 and younger at the time of diagnosis. Categorical variables were compared with the chi-square test, and continuous variables with Student t test or Mann–Whitney U test, as appropriate. Logistic regression modeling was used to assess the use of chemotherapy.
Results Demographics Of the 10,433 patients, 7,354 (70.5%) were ⱕ79 and 3,789 (29.5%) were ⱖ80 years old. Patients ⱖ80 years of age were more likely to be female and less likely to live in a rural county than the younger patients (Table 1).
Methods
Tumor characteristics and stage at diagnosis
Database
Older patients were less likely to have stages in situ, regional to lymph node direct extension, or distant metastatic disease at presentation, but they were more likely than younger patients to have disease that was regional by direct
The Oregon Health & Science University Institution Review Board and the Oregon State Cancer Registry (OSCaR)
Figure 1 Stage at diagnosis. Reg by Dir Ext ⫽ regional by direct extension; Reg to LN’s ⫽ regional to lymph nodes; Reg to LN ⫹ DE ⫽ regional to lymph nodes and direct extension; Distant Mets ⫽ distant metastasis.
626
The American Journal of Surgery, Vol 197, No 5, May 2009
extension or unknown stage (Figure 1). Tumors in patients ⱖ80 years of age were more likely to be proximal to the splenic flexure (59.5 vs 47.8, P ⬍.001). And, older patients had positive lymph nodes in 32% of the specimens removed versus 40% for younger patients (P ⬍.001) (Table 1).
disease (Figure 3A). When chemotherapy was given to patients ⱖ80 years of age, they were significantly less likely to receive multi-agent chemotherapy (Figure 3B). Multivariate logistic regression analysis of predictors of receiving chemotherapy for each of the 2 age groups was performed. Predictors of receiving chemotherapy were different for patients ⱖ80 than for patients who were 79 or younger. Predictors in older patients included increased age, worse stage of disease, and living in an urban environment, but predictors in younger patients were worse stage and having fewer lymph nodes removed. Year of diagnosis and sex of the patient were not predictive of receiving chemotherapy in either age group.
Treatment Patients who were ⱖ80 years old were less likely to have surgery if the stage was regional by direct extension, distant metastasis, or unknown, but they were just as likely to have surgery for any other stage as younger patients (Figure 2A). Patients ⱖ 80 years old had significantly fewer lymph nodes retrieved at surgery (10 vs 11, P ⬍.05). However, when the data were split according to year of diagnosis, only 2,004 had a significant difference in lymph node retrieval (11 vs 14, P ⫽ .001) (Figure 2B). Chemotherapy was given to patients ⱖ80 years old significantly less often than younger patients for every stage of
Comments The US population is becoming increasingly older, but data on how best to care for these patients are sparse. The
Figure 2 (A) Stage at diagnosis vs percentage of patients having a colectomy. Reg by Dir Ext ⫽ regional by direct extension; Reg to LN’s ⫽ regional to lymph nodes; Reg to LN ⫹ DE ⫽ regional to lymph nodes and direct extension; Distant Mets ⫽ distant metastasis. (B) Number of lymph nodes vs year at diagnosis.
K.M. Hardiman et al.
Treatment of colon cancer in octogenarians
627
Figure 3 (A) Percentage of patients receiving chemotherapy for each stage. Reg by Dir Ext ⫽ regional by direct extension; Reg to LN’s ⫽ regional to lymph nodes; Reg to LN ⫹ DE ⫽ regional to lymph nodes and direct extension; Distant Mets ⫽ distant metastasis. (B) Type of chemotherapy given.
purpose of this study was to examine disparities in treatment of colon cancer related to age using a large state database. Unfortunately, much of the key research guiding our current standard of care for diseases such as colon cancer has not included those over 80 years of age. This may in part be due to the ever-changing definition of “elderly.” In our study, about a third of Oregon’s population with colon cancer was age 80 or older. Their disease did not have the same stage distribution as in the younger patients, but this was likely due to the number of patients whose stage was unknown. The treatment of the patients age 80 and older was different from that of their younger counterparts. This agrees with prior smaller studies such as that reported by Mahoney et al, who showed that 34% of patients age 80 or older are not even offered chemotherapy.8 While medical comorbidities might preclude its use in some patients, what is concerning is how little chemotherapy these older patients are receiving. The limited data available do indicate that older patients benefit from receiving chemotherapy, and that age does not diminish the increase in survival derived from the chemotherapy.7,9 This area clearly warrants further study to help delineate which
patients will benefit from chemotherapy, to what degree, and at what cost. With respect to surgical therapy, our study shows that patients age 80 or older were less likely to have a colectomy for advanced or metastatic disease, but they were just as likely to undergo a colectomy for local disease when compared to younger patients. This is consistent with other studies showing an excellent rate of surgical intervention for colorectal cancer among patients age 80 or older.10 The morbidity of colectomy, or even metastatectomy, is favorable in well-selected elderly patients. Mazzoni et al showed in a small study that even liver resection for colorectal metastasis is justified for selected patients over 70 years old.11 While many elderly patients in our study did have surgical treatment of their cancer, fewer lymph nodes were resected from older patients. This may be due to surgical factors, such as less extensive resections, or patient factors, such as smaller or fewer nodes in the elderly.12 The less extensive lymph node evaluation may have led to understaging of the elderly patients in this study, as there were fewer patients with positive nodes among the elderly pa-
628
The American Journal of Surgery, Vol 197, No 5, May 2009
tients. The evaluation of an adequate number of lymph nodes may be an important quality marker in the elderly. Bilimoria et al recently showed that the improved survival benefit derived from examination of 12 or more lymph nodes was present in all age groups including patients age 78 and older.13 A weakness of this study was its retrospective design using only a database for information. This database did not report patient comorbidities that would have played a role in the decision for treatment. The database lacked information regarding treatments offered but not received, which could significantly affect the number of patients ⱖ80 years of age receiving chemotherapy and/or surgery. Mortality and recurrence of disease were also absent. In summary, nearly one third of colon cancers in Oregon are diagnosed in patients ⱖ80 years old. Treatment of these patients appears to be different based on age. In the growing elderly population, there are few well-conducted trials and ill-defined guidelines, which may result in differences in treatment. The average 80-year-old person is expected to survive ⬎5 years, and it is unclear whether the differences in treatment of elderly patients are justified. More research into the proper care of those 80 and older would help to establish consistent guidelines for colon cancer treatment.
References
Acknowledgment The authors would like to acknowledge the hard work of the staff of the Oregon State Cancer Registry, Oregon Department of Human Services, Portland, OR.
1. CensusScope, population pyramid and age distribution statistics. University of Michigan. Available from: http://www.censusscope.org/us/ chart_age.html. Accessed November 1, 2008. 2. Arias E. US Life Tables, 2003. United States Department of Health and Human Services, Centers for Disease Control and Prevention; 2006 April 19. Report No. 54. 3. Trimble E, Carter C, Cain D, et al. Representation of older patients in cancer treatment trials. Cancer 1994;1:2208 –14. 4. Murthy VH, Krumholz HM, Gross CP. Participation in cancer clinical trials: race-, sex-, and age-based disparitie. JAMA 2004;291:2720 – 6. 5. Andre T, Boni C, Mounedji-Boudiaf L, et al. Oxaliplatin, fluorouracil, and leucovorin as adjuvant treatment for colon cancer. N Engl J Med 2004;350:2343–51. 6. Sundararajan V, Grann VR, Jacobson JS, et al. Variations in the use of adjuvant chemotherapy for node-positive colon cancer in the elderly: a population-based study. Cancer 2001;7:213– 8. 7. Jessup JM, Stewart A, Greene FL, et al. Adjuvant chemotherapy for stage III colon cancer: implications of race/ethnicity, age, and differentiation. JAMA 2005;294:2703–11. 8. Mahoney T, Kuo Y, Topilow A, et al. Stage III colon cancers: why adjuvant chemotherapy is not offered to elderly patients. Arch Surg 2000;135:182–5. 9. Iwashyna TJ, Lamont EB. Effectiveness of adjuvant fluorouracil in clinical practice: a population-based cohort study of elderly patients with stage III colon cancer. J Clin Oncol 2002;20:3992– 8. 10. O’Connell J, Maggard M, Ko C. Cancer-directed surgery for localized disease: decreased use in the elderly. Ann Surg Oncol 2004;11:962–9. 11. Mazzoni G, Tocchi A, Miccini M, et al. Surgical treatment of liver metastases from colorectal cancer in elderly patients. Int J Colorectal Dis 2007;22:77– 83. 12. Lemmens V, Lijnschoten I, Janssen-Heijnen M, et al. Pathology practice patterns affect lymph node evaluation and outcome of colon cancer: a population-based study. Ann Oncol 2006;17:1803–9. 13. Bilimoria KY, Stewart AK, Palis BE, et al. Adequacy and importance of lymph node evaluation for colon cancer in the elderly. J Am Coll Surg 2008;206:247–54.