Since the advent of population-based breast cancer screening and digital mammography, the prevalence of ductal carcinoma in situ (DCIS) has increased more than fivefold in Western countries. DCIS is seen in 25% to 30% of newly diagnosed breast cancers.
However, there is rising concern about overtreatment of low-risk DCIS. To address this, the PRECISION Cancer Grand Challenge Consortium was founded to provide more precise risk classification for DCIS. Â
Even if there is a link between the two, not all cases of DCIS advance to invasive disease. As a result, despite minimal evidence of a reduction in breast cancer mortality, most women with DCIS are treated with mastectomy or breast conserving surgery, often followed by radiation or endocrine treatment. Â
A big global research aiming at putting light on this topic assessed the probability of developing ipsilateral invasive breast cancer and ipsilateral DCIS across a variety of DCIS size and margin status variables. The study’s goal was to see if women would be good candidates for therapy de-escalation in order to avoid overtreatment of women with low-risk DCIS. Â
Using large, previously produced cohorts, researchers investigated if variables may contribute to the development of invasive breast cancer or DCIS on the same side as the original DCIS diagnosis. The capacity to generalize results was made possible by using global patient-level data from worldwide registries.
The study discovered that including the margins during breast conserving surgery for women with DCIS doubled the likelihood of developing ipsilateral invasive breast cancer, regardless of whether the women had undergone radiation therapy.
The probability of ipsilateral DCIS rose as the main tumor grew larger. In individuals with greater DCIS, the probability of getting invasive breast cancer on the same side was marginally enhanced. Â
According to Harrell’s C indices, the clinical relevance of these variables is low at best. Larger DCIS (50 mm) was related with a higher risk of stage III and IV ipsilateral invasive breast cancer than smaller DCIS (20 mm). There was no link seen between having an inflamed margin and having advanced ipsilateral invasive breast cancer.Â
One of the study’s benefits was its use of a large, global registry data collection, which allowed for the generalizability of its findings. It was not without problems, however, including data gaps and the possibility of altering baseline risks between cohorts and nations. Â
This study adds to the evidence that DCIS is low-risk by revealing that the cumulative incidence of ipsilateral invasive breast cancer was 3.2% during a 10-year period. These findings highlight the need of identifying high-risk DCIS patients in order to avoid wasteful treatments and enhance DCIS care.
The potential benefit of endocrine therapy in select situations was also emphasized, however the study did notice differences in results from previous randomized trials. Current studies and future research will provide additional information on how to effectively treat DCIS. Â
Journal Reference Â
Schmitz, R. S. J. M., Belt-Dusebout, A. W. van den, Clements, K., Ren, Y., Cresta, C., Timbres, J., … Schmidt, M. K. (2023). Association of DCIS size and margin status with risk of developing breast cancer post-treatment: multinational, pooled cohort study. Retrieved from https://www.bmj.com/content/383/bmj-2023-076022Â
