Tumour Bed Boost May Reduce QoL After Breast-Conserving Therapy

Author: By Lynda Williams, Senior medwireNews Reporter 

medwireNews: Use of tumour bed boost and hypofractionation may have a detrimental impact on some patient-reported outcomes at 2 years, indicates a study of women undergoing breast-conserving surgery and adjuvant whole-breast radiotherapy (WBRT) for non-low-risk ductal carcinoma in situ.  

“Pending efficacy analysis of the effects of tumour bed boost and whole breast radiotherapy dose-fractionation on time to local recurrence (the primary study endpoint of the BIG 3-07/TROG 07.01 trial), the PRO data presented here support shared treatment decision making between patients with ductal carcinoma in situ and their clinicians”, the investigators write in The Lancet Oncology.

The trial included three randomisation categories for patients recruited in Australasia and south east Asia, the UK and Ireland, continental Europe, and Canada. Overall, 396 category A patients were randomly assigned in category A to receive WBRT (50 Gy in 25 fractions over 5 weeks) without a boost, 100 patients to receive hypofractionated WBRT (42.5 Gy in 16 fractions over 3.5 weeks) without boost, 100 patients to receive conventional WBRT and 98 to receive hypofractionated WBRT plus boost. 

A further 447 patients in category B to receive conventional WBRT with (n=223) or without boost (n=224), while 365 category C patients were assigned to a regimen of hypofractionated WBRT with (n=182) or without (n=183) boost. 

Overall, 91% of patients completed treatment; 95% completed baseline health-related quality of life (HRQoL) surveys and 87% did so at the 2-year checkpoint, say Madeleine King, from the University of Sydney in New South Wales, Australia, and co-workers. 

As demonstrated by Breast Cancer Treatment Outcome Scale (BCTOS)-cosmetic status assessments, all patients experienced a decrease in cosmetic status between baseline and the end of treatment but this was significantly worse for those who received a tumour bed boost. And although both groups experienced cosmetic improvements by 12 and 24 months, a significant difference continued during these periods. 

Similarly, all patients experienced a decline in their BCTOS scores for arm- and shoulder-specific function between baseline and the end of treatment, but this was significantly greater in patients who did versus did not receive a tumour bed boost. And significant differences continued to persist at 12 and 24 months between the groups. 

Madeleine King et al report that patients who did not receive a boost experienced a return to baseline values by 12 months for both the cosmetic and functional measures, whereas the tumour bed boost group experienced “small, but clinically important” differences in arm and shoulder function at 6 months, and “persistent asymmetry (ie, poor cosmetic outcomes)” at 24 months. 

However, there no differences noted between patients who did and did not receive tumour bed boost with regard to the other PROs of breast-specific symptoms, body image and sexuality, fatigue, physical functioning, cancer worry, or perceived risk of invasive breast cancer. 

Patients who received hypofractionated radiotherapy had “markedly worse” outcomes for body image and sexuality at the end of treatment but the researchers say “this difference diminished with time.” 

John Benson, from Addenbrooke’s Hospital in Cambridge, UK, writes in an linked comment that “longer follow-up is required to fully assess breast fibrosis and other chronic sequelae in this study population” and that  [e]fficacy data will provide crucial information on whether a boost and potential cosmetic failure is justified for selected patients based on estimates of likely recurrence.” 

Noting that a “risk-stratified approach” might be used to consider the use of tumour bed boost for patients with “inadequate” re-excision or “when tumour biology portends invasive relapse”, he concludes:  “In an era of patient-centric care, these data collectively allow patients to be better informed about the cosmetic risks of any recommendation for tumour bed boost pending definitive level I evidence on efficacy in relation to levels of individual risk.” 

References 

King MT, Link EK, Whelan TJ, et al. Quality of life after breast-conserving therapy and adjuvant radiotherapy for non-low-risk ductal carcinoma in situ (BIG 3-07/TROG 07.01): 2-year results of a randomised, controlled, phase 3 trial. Lancet Oncol; Advance online publication 20 March 2020. https://doi.org/10.1016/S1470-2045(20)30085-1

Benson JR. Quality of life after brast-conserving surgery for women with non-low-risk ductal carcinoma in situ. Lancet Oncol; Advance online publication 20 March 2020. https://doi.org/10.1016/S1470-2045(20)30135-2