Radiotherapy for invasive breast cancer: guidelines for clinical practice from the French expert review board of Nice/Saint-Paul de Vence

Purpose: While new strategies for the treatment of invasive breast cancer (BC) are emerging, radiotherapy (RT) modalities are still under debate. The French expert review board of Nice-Saint-Paul de Vence was asked firstly to conduct a qualitative evidence-based systematic review and then to establish clinical practice guidelines for the use of post operative RT in invasive BC.

Methods and materials: A search to identify eligible studies was undertaken using the Medline® database. All phase III randomized trials and systematic reviews evaluating the role and modalities of RT in invasive BC were included, together with some noncontrolled studies if no randomized trials were identified. The quality and clinical relevance of the studies were evaluated to determine the level of evidence.

Results: The maximum delay between surgery and RT should ≤8 weeks when chemotherapy (CT) is not indicated. This should not exceed 24 weeks when adjuvant CT is administered. Whole breast RT delivering 50 Gy in 25 fractions followed by a boost of 10-16 Gy remains the standard of care after conservative surgery (CS). In the elderly population, for certain cases presenting comorbidities associated with a limited life expectancy, RT indication (even hypofractioned) and boost delivery may be unnecessary in the light of an unfavourable risk/benefit ratio. RT technique and indications should not vary in case of neoadjuvant CT followed by CS. After total mastectomy, RT should be indicated in N+ and in N- patients with high risk of local recurrence. The experts recommend to initiate tamoxifen at the end of RT, while aromatase inhibitors could be administered either concomitantly or sequentially with RT. There is no consistent data to delay (or suspend) trastuzumab administration during RT. As for all patients, in case of concurrent RT-trastuzumab administration, reduction of cardiac tissues exposure is highly recommended. After breast reconstruction, RT should be delivered as after standard CS without boost.

Conclusion: Due to significant variations in practice in the treatment of patients with BC, our group aimed to provide guidelines for clinical practice. The systematic review of the literature formed the basis of our evidence-based recommendations; however expert agreements were necessary on those subjects that are still under debate. Our group will update these guidelines every 4 years, taking in consideration new advances in technology, new drugs administration, biologic tools and innovative therapeutic options.