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Comparison of Three Treatment Schemes for Lung SBRT
I. J. Radiation Oncology d Biology d Physics
S182
Volume 78, Number 3, Supplement, 2010
Materials/Methods: A prospective registry of 253 patients with 270 primary (n = 252) or metastatic (n = 18) lung lesions treated with lung SBRT at Mallinckrodt Institute of Radiology from 2004-2009 was explored to identify patients (1) treated to a dose of 54 Gy in 3 fractions or 50 Gy in 5 fractions, with (2) at least 3 months (mo) follow-up, and (3) no prior radiotherapy to the ipsilateral thorax or CW. One hundred seventy-six lesions in 167 patients were identified, and complete dosimetric data was available on 110 CWs. The ipsilateral CW (defined as a 3 cm outward expansion from the ipsilateral lung) and ribs were contoured on each patient. Patient related risk factors for CW toxicity were analyzed on all 167 patients. Univariate analysis and multivariate logistic regression modeling was used to correlate patient, tumor, and dosimetric factors (volume of CW or ribs receiving 5-80 Gy [V5-85] in 5 Gy increments, prescription isodose line, max dose at 2 cm from the PTV) to the development of CW toxicity. Spearman’s rank correlation was used for measuring bivariate associations. Results: Median follow-up was 11.5 months. Nineteen patients (11.4%) developed CW toxicity (8 with rib fracture, 11 with CW pain only). Median time to CW toxicity was 10.8 months (18.6 months for rib fracture, 7.9 months for CW pain only). Patient factors that correlated with CW toxicity on univariate analysis were prior or current tobacco use, connective tissue disorder, and elevated body mass index (p = 0.0308, p = 0.0348, and p = 0.0315, respectively). CW V5-85 all correlated positively with CW toxicity on univariate analysis. CW V65 . 0 cc was most predictive (p = 0.0046). The prescription isodose line correlated negatively with CW toxicity (p = 0.012), such that patients treated to a prescription isodose line of 60-69.9%, 70-79.9%, and $ 80% experienced a 20%, 15%, and 7% rate of CW toxicity, respectively. Both V65 and prescription isodose line correlations remained significant on multivariate analysis. Conclusions: V65 is the dominant variable in the development of CW toxicity in our dataset. Although adequate tumor coverage should not be compromised, we recommend limiting the max dose of the CW to \ 65 Gy if possible. Author Disclosure: K.M. Creach, None; R. Al-lozi, None; I. El Naqa, None; J.D. Bradley, None; J.R. Olsen, None; P.J. Parikh, None; R.E. Drzymala, None; C. Bloch, None; C.G. Robinson, None.
1093
Comparison of Three Treatment Schemes for Lung SBRT
J. R. Olsen, C. G. Robinson, I. El Naqa, K. M. Creach, R. E. Drzymala, C. Bloch, P. J. Parikh, J. D. Bradley Washington University in St. Louis, St. Louis, MO Purpose/Objective(s): The optimal stereotactic body radiation therapy (SBRT) dose and fractionation schedule for lung cancer treatment is unknown. We evaluated local control and overall survival in a large institutional cohort treated with one of three regimens. Materials/Methods: Between 2004 and 2009, 132 patients underwent definitive lung cancer SBRT at Mallinckrodt Institute of Radiology to a single lesion under an IRB approved prospective registry protocol. No patient had any known malignancy for 2 years preceding lung cancer diagnosis, and pathologic diagnosis was confirmed in 110. All prescriptions incorporated heterogeneity corrected dose calculations. We delivered 18 Gy x 3 fractions for peripheral tumors (n = 113) and either 9 Gy x 5 fractions (n = 8) or 10 Gy x 5 fractions (n = 11) for tumors that were central or near critical structures. Results: Median follow-up was 11 (range 3-36), 16 (range 8-25), and 14 (range 3-61) months for the 9 Gy x 5, 10 Gy x 5, and 18 Gy x 3 groups. Local control statistics for years 1 and 2 were 75 and 50% for 9 Gy x 5, 100 and 100% for 10 Gy x 5, and 99 and 91% for 18 Gy x 3. Median overall survival was 14, not reached (10/11 alive), and 36 months for the 9 Gy x 5, 10 Gy x 5, and 18 Gy x 3 treatments. No significant difference in local control or overall survival was found between the 10 Gy x 5 and 18 Gy x 3 groups on log-rank test, but both groups had improved local control (p = 0.006) and overall survival (p = 0.008) compared to 9 Gy x 5. The prescribed total dose and tumor volume correlated with risk of local failure on both univariate (p \ 0.02, p \ 0.02) and on multivariate analysis with increased risk for lower dose fraction regimens (p = 0.06) and larger volumes (p = 0.04). Conclusions: With limited follow-up, 10 Gy x 5 and 18 Gy x 3 regimens appear efficacious for lung cancer SBRT, and provide superior local control and overall survival compared to 9 Gy x 5. Author Disclosure: J.R. Olsen, None; C.G. Robinson, None; I. El Naqa, None; K.M. Creach, None; R.E. Drzymala, None; C. Bloch, None; P.J. Parikh, None; J.D. Bradley, None.
1094
Early Pulmonary Toxicity of Lung Stereotactic Body Radiation Therapy (SBRT) Delivered as Consecutive Daily Fractions
M. C. Stauder, O. K. MacDonald, K. R. Olivier, R. C. Miller, P. D. Brown, Y. I. Garces Mayo Clinic, Rochester, MN Purpose/Objective(s): To identify the incidence of early pulmonary toxicity in patients treated with lung SBRT on consecutive treatment days. Materials/Methods: From January 11, 2008 to January 12, 2010, a total of 91 lesions in 87 patients were treated with SBRT in consecutive daily fractions (Fx) for medically inoperable non-small cell lung cancer or metastatic lung lesions at Mayo Clinic. Lesions were determined to be central if they were within 2 cm of the central bronchial tree as defined in current RTOG lung SBRT protocols. Treatment planning was performed with full body immobilization and 4-dimensional CT-based planning. Tissue heterogeneity corrections were used in all cases. Daily cone-beam CT was used for image guidance. Follow-up care consisted of CT imaging and clinical exam every 3 months. The incidence of pneumonitis was evaluated and graded according to the NCI Common Terminology Criteria for Adverse Events v3.0. Local and locoregional failure was defined as per Response Evaluation Criteria in Solid Tumors. Lesions were excluded from analysis if no post-treatment follow-up was available. Results: Eighty-six lesions in 82 patients met criteria for analysis. With a median follow-up of 7.5 months (range, 1.8-22.4), the median age at the time of initial SBRT was 72.1 years (range, 23.8-87.8). Of the 86 lesions treated with SBRT on consecutive days, 50 lesions were central and 36 were peripheral. 51 (59%) were primary lesions,13 (15%) were recurrent, and 22 (26%) were metastatic. 47 lesions (55%) were treated with 48 Gy in 4 Fx, 27 (31%) with 54 Gy in 3 Fx, 10 (12%) with 50 Gy in 5 Fx, and 1 (1%) each with 60 Gy in 5 Fx and 32 Gy in 4 Fx. The median dose per fraction was 12 Gy (range 8-18 Gy) and the median number of
S182
Volume 78, Number 3, Supplement, 2010
Materials/Methods: A prospective registry of 253 patients with 270 primary (n = 252) or metastatic (n = 18) lung lesions treated with lung SBRT at Mallinckrodt Institute of Radiology from 2004-2009 was explored to identify patients (1) treated to a dose of 54 Gy in 3 fractions or 50 Gy in 5 fractions, with (2) at least 3 months (mo) follow-up, and (3) no prior radiotherapy to the ipsilateral thorax or CW. One hundred seventy-six lesions in 167 patients were identified, and complete dosimetric data was available on 110 CWs. The ipsilateral CW (defined as a 3 cm outward expansion from the ipsilateral lung) and ribs were contoured on each patient. Patient related risk factors for CW toxicity were analyzed on all 167 patients. Univariate analysis and multivariate logistic regression modeling was used to correlate patient, tumor, and dosimetric factors (volume of CW or ribs receiving 5-80 Gy [V5-85] in 5 Gy increments, prescription isodose line, max dose at 2 cm from the PTV) to the development of CW toxicity. Spearman’s rank correlation was used for measuring bivariate associations. Results: Median follow-up was 11.5 months. Nineteen patients (11.4%) developed CW toxicity (8 with rib fracture, 11 with CW pain only). Median time to CW toxicity was 10.8 months (18.6 months for rib fracture, 7.9 months for CW pain only). Patient factors that correlated with CW toxicity on univariate analysis were prior or current tobacco use, connective tissue disorder, and elevated body mass index (p = 0.0308, p = 0.0348, and p = 0.0315, respectively). CW V5-85 all correlated positively with CW toxicity on univariate analysis. CW V65 . 0 cc was most predictive (p = 0.0046). The prescription isodose line correlated negatively with CW toxicity (p = 0.012), such that patients treated to a prescription isodose line of 60-69.9%, 70-79.9%, and $ 80% experienced a 20%, 15%, and 7% rate of CW toxicity, respectively. Both V65 and prescription isodose line correlations remained significant on multivariate analysis. Conclusions: V65 is the dominant variable in the development of CW toxicity in our dataset. Although adequate tumor coverage should not be compromised, we recommend limiting the max dose of the CW to \ 65 Gy if possible. Author Disclosure: K.M. Creach, None; R. Al-lozi, None; I. El Naqa, None; J.D. Bradley, None; J.R. Olsen, None; P.J. Parikh, None; R.E. Drzymala, None; C. Bloch, None; C.G. Robinson, None.
1093
Comparison of Three Treatment Schemes for Lung SBRT
J. R. Olsen, C. G. Robinson, I. El Naqa, K. M. Creach, R. E. Drzymala, C. Bloch, P. J. Parikh, J. D. Bradley Washington University in St. Louis, St. Louis, MO Purpose/Objective(s): The optimal stereotactic body radiation therapy (SBRT) dose and fractionation schedule for lung cancer treatment is unknown. We evaluated local control and overall survival in a large institutional cohort treated with one of three regimens. Materials/Methods: Between 2004 and 2009, 132 patients underwent definitive lung cancer SBRT at Mallinckrodt Institute of Radiology to a single lesion under an IRB approved prospective registry protocol. No patient had any known malignancy for 2 years preceding lung cancer diagnosis, and pathologic diagnosis was confirmed in 110. All prescriptions incorporated heterogeneity corrected dose calculations. We delivered 18 Gy x 3 fractions for peripheral tumors (n = 113) and either 9 Gy x 5 fractions (n = 8) or 10 Gy x 5 fractions (n = 11) for tumors that were central or near critical structures. Results: Median follow-up was 11 (range 3-36), 16 (range 8-25), and 14 (range 3-61) months for the 9 Gy x 5, 10 Gy x 5, and 18 Gy x 3 groups. Local control statistics for years 1 and 2 were 75 and 50% for 9 Gy x 5, 100 and 100% for 10 Gy x 5, and 99 and 91% for 18 Gy x 3. Median overall survival was 14, not reached (10/11 alive), and 36 months for the 9 Gy x 5, 10 Gy x 5, and 18 Gy x 3 treatments. No significant difference in local control or overall survival was found between the 10 Gy x 5 and 18 Gy x 3 groups on log-rank test, but both groups had improved local control (p = 0.006) and overall survival (p = 0.008) compared to 9 Gy x 5. The prescribed total dose and tumor volume correlated with risk of local failure on both univariate (p \ 0.02, p \ 0.02) and on multivariate analysis with increased risk for lower dose fraction regimens (p = 0.06) and larger volumes (p = 0.04). Conclusions: With limited follow-up, 10 Gy x 5 and 18 Gy x 3 regimens appear efficacious for lung cancer SBRT, and provide superior local control and overall survival compared to 9 Gy x 5. Author Disclosure: J.R. Olsen, None; C.G. Robinson, None; I. El Naqa, None; K.M. Creach, None; R.E. Drzymala, None; C. Bloch, None; P.J. Parikh, None; J.D. Bradley, None.
1094
Early Pulmonary Toxicity of Lung Stereotactic Body Radiation Therapy (SBRT) Delivered as Consecutive Daily Fractions
M. C. Stauder, O. K. MacDonald, K. R. Olivier, R. C. Miller, P. D. Brown, Y. I. Garces Mayo Clinic, Rochester, MN Purpose/Objective(s): To identify the incidence of early pulmonary toxicity in patients treated with lung SBRT on consecutive treatment days. Materials/Methods: From January 11, 2008 to January 12, 2010, a total of 91 lesions in 87 patients were treated with SBRT in consecutive daily fractions (Fx) for medically inoperable non-small cell lung cancer or metastatic lung lesions at Mayo Clinic. Lesions were determined to be central if they were within 2 cm of the central bronchial tree as defined in current RTOG lung SBRT protocols. Treatment planning was performed with full body immobilization and 4-dimensional CT-based planning. Tissue heterogeneity corrections were used in all cases. Daily cone-beam CT was used for image guidance. Follow-up care consisted of CT imaging and clinical exam every 3 months. The incidence of pneumonitis was evaluated and graded according to the NCI Common Terminology Criteria for Adverse Events v3.0. Local and locoregional failure was defined as per Response Evaluation Criteria in Solid Tumors. Lesions were excluded from analysis if no post-treatment follow-up was available. Results: Eighty-six lesions in 82 patients met criteria for analysis. With a median follow-up of 7.5 months (range, 1.8-22.4), the median age at the time of initial SBRT was 72.1 years (range, 23.8-87.8). Of the 86 lesions treated with SBRT on consecutive days, 50 lesions were central and 36 were peripheral. 51 (59%) were primary lesions,13 (15%) were recurrent, and 22 (26%) were metastatic. 47 lesions (55%) were treated with 48 Gy in 4 Fx, 27 (31%) with 54 Gy in 3 Fx, 10 (12%) with 50 Gy in 5 Fx, and 1 (1%) each with 60 Gy in 5 Fx and 32 Gy in 4 Fx. The median dose per fraction was 12 Gy (range 8-18 Gy) and the median number of