General Session 2: EUROPA – SUPREMO – COMET

In this video, Dr Kevin Punie discusses and comments on the data of some interesting studies presented during General Session 2 at SABCS 2024. 

The EUROPA trial, presented by Professor Icro Meattini from the University of Florence, explored the outcomes of using either adjuvant endocrine therapy or radiotherapy alone in women aged 70 or older with stage 1, low-proliferative luminal breast cancer. The trial randomised 926 patients with stage 1 HR+ HER2- cancer to receive one of these treatments following surgery. Traditionally, these modalities are combined, but this study questioned whether both are necessary for such a low-risk group. The co-primary endpoints were ipsilateral breast cancer recurrence and quality of life as measured by the EORTC C30 global health score. The interim analysis, which included patients with at least 24 months of follow-up, found no ipsilateral recurrences in either treatment arm, suggesting that both approaches offer favourable short-term outcomes. The quality-of-life analysis, however, revealed significant differences favouring the radiotherapy arm, as endocrine therapy had a more pronounced negative impact on global health scores. This reflects the challenges associated with the prolonged nature of endocrine therapy compared to the shorter course of radiotherapy. These findings suggest that for selected older women with early-stage luminal breast cancer, radiotherapy alone may suffice, potentially sparing them the long-term burden of endocrine therapy.

The SUPREMO trial examined the value of post-mastectomy radiotherapy in women with intermediate-risk breast cancer. Over 1,600 women were randomised to receive either radiotherapy or no radiotherapy after surgery. The trial included patients with 1–3 positive axillary lymph nodes or large tumours without nodal involvement (pT3N0). It aimed to assess overall survival, hypothesising a potential survival benefit from post-mastectomy radiotherapy. However, the results showed no significant difference in overall survival between the two groups, indicating that radiotherapy offered no clear benefit in this intermediate-risk population. An important aspect of this study was that all patients with nodal involvement underwent complete axillary dissection, which may limit the applicability of the findings to contemporary practice, where axillary radiotherapy is often used instead of dissection for patients with limited nodal involvement. While the findings suggest that post-mastectomy radiotherapy can be safely omitted in certain intermediate-risk patients, especially those with node-negative disease or limited nodal involvement following axillary dissection, further research is needed to confirm its relevance for patients managed with newer, less invasive approaches.

The COMET trial investigated whether active surveillance could be a viable alternative to standard care for patients with low-risk ductal carcinoma in situ (DCIS). This randomised non-inferiority study compared protocol-guided standard care (surgery with or without adjuvant radiotherapy) to active surveillance in patients with hormone receptor-positive, grade 1 or 2 DCIS. The primary endpoint was the rate of invasive ipsilateral breast cancer events at two years. The results revealed low rates of invasive events in both groups, with no significant differences, suggesting that active surveillance may be a safe option for managing low-risk DCIS. However, most invasive events in the standard care arm were identified through surgical upstaging, highlighting the challenge of accurate pre-surgical risk stratification. The trial also assessed patient-reported outcomes, finding no significant differences in overall quality of life or anxiety between the groups. However, patients in the active surveillance arm experienced fewer symptoms, such as pain and arm discomfort, compared to those who underwent surgery. Despite these promising results, the short two-year follow-up limits definitive conclusions about long-term safety and efficacy. Therefore, while the study offers encouraging evidence for active surveillance in selected patients, longer-term data and additional studies are needed before this approach can be widely adopted.