Hypofractionated radiotherapy in post mastectomy locally advanced breast cancer: a study from a regional cancer center in North East India

Abstract

Background: Adjuvant radiotherapy has increased local-regional and overall survival rates in breast cancer. Conventional fractionation delivering 50-60 Gray (Gy) over 5-6weeks is a standard approach. A shorter duration of hypofractionated treatment will be more convenient for patients and treatment providers if found safe and equally effective. Methods: Around 50 high risk breast cancer patients who underwent mastectomy were enrolled and randomized into the study arms-CF (Conventional Fractionation) Arm (50Gy/25 Fr @ 2 Gy/fraction/day 5 days a week over 5weeks) and HF (Hypo-Fractionation) arm (40.05 Gy/15 Fr @ 2.67 Gy/fraction/day 5 days a week over 3weeks). Treatment related acute and late toxicities, loco-regional recurrence; distant metastasis and survival rates were recorded for comparison. Results: Twenty-five patients were enrolled in each arm with baseline characters well matched. At median follow up of 44 months, OS was 80% in HF arm against 64% in CF arm (p-value: 0.292). HF arm also showed better DFS at 4 years of 76% compared to 64% in CF arm (p-value: 0.411). Although the difference was not significant statistically, the Hazard Ratio of 1.543 (95% CI: 0.549-4.339) for DFS and 1.801 (95% CI: 0.603-5.377) for OS indicated trends towards better outcomes in HF arm in terms of disease control and survival. Acute and late toxicities were also lesser in HF arm, though not statistically significant (all p-values >0.05). Conclusions:In post mastectomy setting, HFRT is comparable to CFRT in terms of safety and efficacy, will be more convenient for patients and care givers and hence can be a routine standard practice.

Hypofractionated radiotherapy in postmastectomy locally advanced breast cancer: an interim report on acute toxicities and dosimetry

“…This was based on the 96% prevalence of good local control in patients treated with hypofractionated radiotherapy after 44 months of follow-up. 12 Critical value approach (hypothesis testing) applying two-tailed distribution was used to derive the sample size, which accounted for a power of 80% and a 5% level of significance. The null hypothesis was that hypofractionated PMRT leads to local control rates of 96%, while the alternative hypothesis was that it does not lead to local control rates of 96%.…”

“…The proportion for the alternative hypothesis was set at 88% based on the prevalence of patients treated with conventional fractionation who had good local control. 12 This resulted in critical values of 77 and 84, implying that if the number of patients with good local control is equal to or greater than 84, or less than or equal to 77, then the null hypothesis may be rejected. For this study, a sample size of 92 was used to account for attrition.…”

“…This was based on the 96% prevalence of good local control in patients treated with hypofractionated radiotherapy after 44 months of follow-up. 12 loco-regional recurrence; distant metastasis and survival rates were recorded for comparison.Results: Twenty-five patients were enrolled in each arm with baseline characters well matched. At median follow up of 44 months, OS was 80% in HF arm against 64% in CF arm (p-value: 0.292 Critical value approach (hypothesis testing) applying two-tailed distribution was used to derive the sample size, which accounted for a power of 80% and a 5% level of significance.…”

“…The proportion for the alternative hypothesis was set at 88% based on the prevalence of patients treated with conventional fractionation who had good local control. 12 loco-regional recurrence; distant metastasis and survival rates were recorded for comparison. Results: Twenty-five patients were enrolled in each arm with baseline characters well matched.…”

“…An increasing number of retrospective [ 9 , 10 ] and prospective [ 11 , 12 ] trials have been conducted that support the use of hypofractionated PMRT, utilizing a variety of fractionation regimens. However, to date, there is only one randomized, phase III trial that compared conventional fractionated PMRT with hypofractionated PMRT [ 13 ].…”