Protein Marker Can Predict 10-Year Radiotherapy Efficacy for DCIS

Women who have lower levels of a fibroblast protein that is integral to the development of the cardiovascular system – PDGFRb – have a better response to radiotherapy treatment for early-stage breast cancer.

For ductal carcinoma in situ (DCIS), the current treatment is surgery and subsequent radiotherapy. Long-term outcomes are generally good, but up to 10 percent of women do suffer a recurrent within 10 years. Consequently, unearthing a more personalized way to treat these women is vital, said investigators from Karolinska Institutet and Gothenburg University in Sweden.

“It is well known that the benefits of radiotherapy are individual, so we need to find predictive markers that can be used to avoid unnecessary or ineffective radiotherapy,” said Fredrik Wärnberg, professor in the clinical sciences department at Gothenburg University’s Sahlgrenska Academy.

The team, co-led by Wärnberg, published their findings recently in Clinical Cancer Research.

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Instead of focusing on markers within the tumor cells, the team pivoted to examine the role cells surrounding the tumor might play in the efficacy of radiotherapy. To do so, researchers analyzed a large tissue collection from a randomized radiotherapy study (SweDCIS), and they found that women who have low PDGFRb levels have better outcomes with radiotherapy for ipsilateral breast events (IBE).

Specifically, women with low PDGFRb experience an absolute risk reduction of recurrence of 21 percent at 10 years. This predictive effect was equally strong for women with in situ and invasive IBE. Unfortunately, women with high PDGFRb levels did not see a significant risk reduction.

These results, the team said, support the possibility of changing approaches to therapy.

“The treatment guidelines of DCIS might need to be changed if these studies confirm our original findings,” said first author Carina Strell, a researcher oncology-pathology department at Karolinska Institutet.

Additional work is underway to investigate whether radiotherapy efficacy can be further improved by blocking PDGFRb.