CANTO‐RT: Skin toxicities evaluation of a multicentre large prospective cohort of irradiated patients for early‐stage breast cancer

Abstract

Skin damage is the most common and most important toxicity during and after radiation therapy (RT). Its assessment and understanding of the factors influencing its occurrence, is a major issue in the management of patients irradiated for an early breast cancer. CANTO is a prospective clinical cohort study of 10 150 patients with stage I‐III BC treated from 2012 to 2017 in 26 cancer centres. In our study, we used CANTO‐RT, a subcohort of CANTO, including 3480 patients who received RT. We are focus on specific skin toxicities: erythema, fibrosis, telangiectasia and cutaneous pigmentation. The prevalence of toxicities of interest varied over time, so at baseline for early toxicity Month (M) 0‐3‐6, 41.1% of patients had erythema while 24.8% of patients had fibrosis. At M12 and M36, the prevalence of erythema decreased, respectively, while fibrosis remains stable. The prevalence of telangiectasia increases from 1% to 7.1% from M0‐3‐6 to M36. After adjustments, we showed an association between the occurrence of skin erythema and obesity; the type of surgery; the presence of axillary dissection; the use of taxane‐based CT and the 3D vs IMRT irradiation technique. Regarding fibrosis, an association is found, at M0‐3‐6, with age at diagnosis, obesity, tobacco and the use of boost. Only obesity and the type of surgery received by the patient remained statistically significant at M12 and M36. In our study we identified several risk factors for acute and late skin reactions. The use of a boost was mainly related to the occurrence of fibrosis while the use of IMRT‐type technique decreased the occurrence of skin erythema.

Concurrent Olaparib and Radiotherapy in Patients With Triple-Negative Breast Cancer

“…The late toxicity profile was similar to that commonly observed with standard radiotherapy protocols. 16 These results suggest that use of olaparib as a radiosensitizer during breast radiotherapy may not be associated with an increased risk of late complications. Therefore, we recommend a radiosensitizing dose of 200 mg twice daily when combining olaparib with breast radiotherapy for future trials assessing the antitumor efficacy of this combination.…”

“…In addition, when indicated, tumor bed boosts were delivered using a volumetricmodulated arc therapy technique, which may be associated with lower incidence of skin toxic effects compared with other techniques. 16 Furthermore, we cannot rule out that some AEs might have been missed due to the follow-up intervals. Of note, although veliparib and olaparib have similar molecular mechanisms, preclinical studies have described notable differences in drug pharmacokinetics, 19,20 which might have led to the difference in tolerance profiles.…”

“…In addition, with a median follow-up of 34 months, only 1 patient developed late treatment-related grade 2 AEs, and no late grade 3 or greater treatment-related AEs were observed, demonstrating the safety of this combination treatment for this indication. The late toxicity profile was similar to that commonly observed with standard radiotherapy protocols . These results suggest that use of olaparib as a radiosensitizer during breast radiotherapy may not be associated with an increased risk of late complications.…”

“…Another explanation for the difference may be the prescribed radiation doses since no scar boost was performed for postmastectomy radiotherapy in our study. In addition, when indicated, tumor bed boosts were delivered using a volumetric-modulated arc therapy technique, which may be associated with lower incidence of skin toxic effects compared with other techniques . Furthermore, we cannot rule out that some AEs might have been missed due to the follow-up intervals.…”

CANTO skin: Evaluation of skin toxicity risk factors in patients treated for breast cancer

“…In our study, we are interested in a larger population and with a longer follow‐up than in our first CANTO‐RT study in larger population of patients 7 . We evaluate all tumour, individual and therapeutic characteristics influencing the occurrence of skin toxicity in patients treated for early breast cancer.…”