A Pilot Study of CONcurrent ChEmotherapy and RadioTherapy in Adjuvant Treatment of Breast Cancer (CONCERT)

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<h3>Purpose/Objective(s)</h3> The study hypothesis was that concurrent adjuvant chemoradiation (CTRT) is safe in adjuvant treatment of breast cancer. This was tested in a prospective interventional pilot study with dose-limiting toxicity as the primary endpoint. It also assesses the compliance rate, toxicity rate and short-term disease related outcomes. CTRI/2019/02/017411 <h3>Materials/Methods</h3> Stage II-III invasive breast cancer patients who were planned for adjuvant taxane-based chemotherapy and adjuvant radiotherapy were screened for the study during April 2019 to December 2020. Patients received standard 3D conformal radiotherapy (40 Gy in 15 fractions over 3 weeks ± boost in case of breast conservation) which was started with the third cycle of adjuvant taxanes in a 3-weekly schedule, or with the eighth cycle of adjuvant taxanes in weekly schedule. <h3>Results</h3> Sixty patients were analyzed. Median age of the study cohort was 46 years (28-66 years). Large majority (60%) women were pre-menopausal and had ECOG performance status 0 (95%) 32 patients (54%) had right sided tumors. Patients either underwent breast conservation surgery (48%) or modified radical mastectomy (52%) with axillary sampling in only small proportion of the patients (20%). 59 patients (98%) received all four cycles of anthracycline based chemotherapy (50 in the neoadjuvant setting) All the patients were compliant with taxane based chemotherapy with dose reduction in three patients in view of peripheral neuropathy. All patients completed adjuvant radiotherapy without any treatment interruption either for taxanes or radiotherapy. No dose-limiting toxicity was documented for any patient. Minimal chemotherapy-related toxicities have been reported in the form of 7 patients (11.6%) having Grade I-II fatigue and 8 patients (13.3%) having Grade I-II peripheral neuropathy. Radiotherapy-related toxicity was also minimal. The incidence of grade 0, 1 and 2 dermatitis were 4%, 84% and 12% respectively while grade 0, 1 and 2 dysphagia were 31%, 57 and 12% respectively. There was no difference between weekly and 3-weekly regimens with respect to compliance rate or toxicity. Dermatitis as well as dysphagia subsided completely by 4 weeks post-completion of CTRT. The median duration between first and last cycle of taxanes was 74 days (range 62 to 107) and radiotherapy start and conclusion was 23 days (range 19 to 28). Four patients had recurrence, one had local and distant recurrence and rest had distant recurrence only. At the median follow up of 23 months, median DFS of 17.5 months (9-22 months) and median OS of 26 months (11-33 months). The 3-year actuarial rate of DFS and OS was 75% and 98.3% respectively. <h3>Conclusion</h3> Concurrent taxane-based adjuvant CTRT is safe and feasible alternative to sequential chemotherapy and radiotherapy. There is minimal toxicity and excellent compliance for both 3-weekly as well as weekly schedules. Hence, it will be worthwhile to test concurrent CTRT in randomized setting with health-economics and disease-related endpoints.