- Email: [email protected]
A comparison of pediatric and adult desmoid tumors treated with radiation therapy
Proceedings of the 43rd Annual ASTRO Meeting
2354
A Comparison of Pediatric and Adult Desmoid Tumors Treated with Radiation Therapy
C.A. Biggs, W.M. Wara, T.L. Phillips, J.O. Johnston, R.J. O’Donnell, V. Weinberg, D.A. Haas-Kogan Radiation Oncology, University of California San Francisco, San Francisco, CA Purpose: Recent series of pediatric desmoid tumors report poor clinical outcome following radiation therapy. We therefore sought to compare the clinical outcome of pediatric and adult desmoid tumors treated with radiation. Materials and Methods: Fifteen children ⱕ18 years of age, and 26 adults ⬎18 years of age were treated for desmoid tumors between 1970 and 2000 using radiation as definitive therapy or as adjuvant treatment following surgical resection. In this retrospective study the pediatric and adult cohorts had comparable follow-up time, accrual periods, gender distributions and treatment parameters. The mean age was 11.6 years (range 3.6-17.6) and 37.9 years (range 18.5-67.5) for the pediatric and adult groups, respectively and the median follow-up was 3.7 years (range 1.0-16.2) and 3.6 years (range 0.1-29.4), respectively. All locoregional failures were documented as either within (in-field) or outside the field of radiation. Distributions between age cohorts in presenting features were compared using the nonparametric Mann-Whitney test. The log-rank test was performed to compare freedom from recurrence between subsets. Results: In-field recurrence rates significantly differed between the pediatric and adult cohorts (p⫽0.01). Six of 7 recurrences in the pediatric group were within the field of radiation while only 1 of 6 relapses in the adult group was in-field. All in-field recurrences occurred in patients younger than 22 years of age. The overall recurrence rates did not significantly differ between these two groups (p⫽0.34). The external-beam radiation dose did not significantly differ between the two cohorts, with a mean dose of 52.0 Gy and 53.8 Gy for pediatric and adult patients, respectively (p⫽0.32). Among the children, seven were treated at primary presentation and eight were treated for recurrent disease, while among the adults, 14 and 11 were treated for primary and recurrent disease, respectively. One out of 5 children and one out of 12 adults with gross disease recurred. Six out of 10 children and 5 out of 14 adults with negative or microscopically positive margins relapsed. Median time-to-recurrence was 4.0 years (range 1.1-4.7) for the pediatric group, while not yet reached for the adult group (range 0.8-3.6). Eleven patients have been followed for longer than 5 years and all are alive and NED. Conclusion: Desmoid tumors arising in children exhibit higher in-field recurrence rates compared with those presenting in adults, suggesting a distinct clinical entity. However, over half of the children did achieve local control following radiotherapy, even in the presence of gross disease. Therefore, the radiation dose administered to children with desmoid tumors should not be compromised, notwithstanding the greater risk of treatment-related toxicity. The use of radiation as a component of multimodality therapy, as well as alternative boost techniques such as intraoperative radiation and brachytherapy, present appealing approaches to improving local control.
413
2354
A Comparison of Pediatric and Adult Desmoid Tumors Treated with Radiation Therapy
C.A. Biggs, W.M. Wara, T.L. Phillips, J.O. Johnston, R.J. O’Donnell, V. Weinberg, D.A. Haas-Kogan Radiation Oncology, University of California San Francisco, San Francisco, CA Purpose: Recent series of pediatric desmoid tumors report poor clinical outcome following radiation therapy. We therefore sought to compare the clinical outcome of pediatric and adult desmoid tumors treated with radiation. Materials and Methods: Fifteen children ⱕ18 years of age, and 26 adults ⬎18 years of age were treated for desmoid tumors between 1970 and 2000 using radiation as definitive therapy or as adjuvant treatment following surgical resection. In this retrospective study the pediatric and adult cohorts had comparable follow-up time, accrual periods, gender distributions and treatment parameters. The mean age was 11.6 years (range 3.6-17.6) and 37.9 years (range 18.5-67.5) for the pediatric and adult groups, respectively and the median follow-up was 3.7 years (range 1.0-16.2) and 3.6 years (range 0.1-29.4), respectively. All locoregional failures were documented as either within (in-field) or outside the field of radiation. Distributions between age cohorts in presenting features were compared using the nonparametric Mann-Whitney test. The log-rank test was performed to compare freedom from recurrence between subsets. Results: In-field recurrence rates significantly differed between the pediatric and adult cohorts (p⫽0.01). Six of 7 recurrences in the pediatric group were within the field of radiation while only 1 of 6 relapses in the adult group was in-field. All in-field recurrences occurred in patients younger than 22 years of age. The overall recurrence rates did not significantly differ between these two groups (p⫽0.34). The external-beam radiation dose did not significantly differ between the two cohorts, with a mean dose of 52.0 Gy and 53.8 Gy for pediatric and adult patients, respectively (p⫽0.32). Among the children, seven were treated at primary presentation and eight were treated for recurrent disease, while among the adults, 14 and 11 were treated for primary and recurrent disease, respectively. One out of 5 children and one out of 12 adults with gross disease recurred. Six out of 10 children and 5 out of 14 adults with negative or microscopically positive margins relapsed. Median time-to-recurrence was 4.0 years (range 1.1-4.7) for the pediatric group, while not yet reached for the adult group (range 0.8-3.6). Eleven patients have been followed for longer than 5 years and all are alive and NED. Conclusion: Desmoid tumors arising in children exhibit higher in-field recurrence rates compared with those presenting in adults, suggesting a distinct clinical entity. However, over half of the children did achieve local control following radiotherapy, even in the presence of gross disease. Therefore, the radiation dose administered to children with desmoid tumors should not be compromised, notwithstanding the greater risk of treatment-related toxicity. The use of radiation as a component of multimodality therapy, as well as alternative boost techniques such as intraoperative radiation and brachytherapy, present appealing approaches to improving local control.
413