Intensity-modulated Radiation Therapy for Anal Cancer: Results From a Multi-Institutional Retrospective Cohort Study

American journal of clinical oncology (Impact Factor: 3.06). 01/2014; DOI: 10.1097/COC.0000000000000009
Source: PubMed


To assess toxicity and efficacy of intensity-modulated radiation therapy (IMRT) for anal cancer.
Records of 152 patients were reviewed retrospectively from multiple institutions. Data on disease control and toxicity were collected as well as patient and treatment characteristics. Acute (<6 mo) and late (≥6 mo) severe toxicity (grade ≥3) were graded. Four patients were excluded due to the presence of metastatic disease or stage TX. Late toxicity data were available for 120 patients.
Median cumulative IMRT dose was 51.25 Gy (median, 28 fractions). All but 2 patients received chemotherapy. With median follow-up of 26.8 months, local control at 3 years was 87%, worse for patients with T3-T4 than T1-T2 disease on univariate analysis (79% vs. 90%; P=0.04). Regional control, distant control, and overall survival were 97%, 91%, and 87%, respectively, at 3 years. Nodal status was associated with regional control, distant control, and overall survival (P<0.01 for each). Most common severe acute toxicity was hematologic (41%), skin (20%), and gastrointestinal tract (11%). Two grade 5 toxicities occurred (hematologic and gastrointestinal tract). Severe late toxicity affected skin (1%) and gastrointestinal tract (3%).
IMRT with chemotherapy resulted in excellent local control. Although T stage predicted worse local control, most T3-T4 disease was controlled with IMRT. Nodal status predicted regional and distant control and overall survival. Severe toxicity was acceptable.

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    ABSTRACT: Background: Chemoradiotherapy (CRT), the primary treatment for anal cancer, achieves complete tumor regression in most patients. Abdominoperineal resection (APR) is reserved for persistent or recurrent disease. An additional boost dose of radiation after CRT often is used to improve the response rate for advanced local disease (T3, 4, and N+). This study examines the need for salvage APR after radiation boost. Methods: Patients with de novo anal cancer in the National Cancer Data Base from the years 2004-2010 were analyzed. Patients with missing data points or who did not receive standard CRT were excluded. Variables included age, gender, race, primary tumor size, clinical nodal status, TNM stage, radiation boost, and APR. A logistic regression model assessing the relationship between boost radiation and APR was developed. Results: Of 1,025 patients meeting inclusion criteria, 450 patients received CRT without a radiation boost and 575 patients received CRT with a radiation boost. The two groups were similar in age, gender, race, tumor size, nodal status, and TNM stage (p values all >0.05). Significant multivariate predictors of salvage APR were tumor size, negative nodal status, and boost RT (all p < 0.05), whereas gender, age, race, and TNM stage were not significant (all p > 0.05). When controlling for age, tumor size, and nodal status, salvage APR is less likely to occur after boost RT (odds ratio 0.63; 95 % confidence interval 0.47, 0.85; p = 0.003). Conclusions: When controlling for age, tumor size, and nodal status, those who received boost radiation for anal cancer were less likely to require salvage APR.
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