Proteins from the calpain family may be associated with improved prognosis in women with breast cancer who received chemotherapy to shrink their tumors prior to surgery, researchers at The University of Nottingham report.

The study, “The calpain system is associated with survival of breast cancer patients with large but operable inflammatory and non-inflammatory tumours treated with neoadjuvant chemotherapy,” published in Oncotarget, revealed a likelihood of better outcomes for women with high levels of calpain in their primary biopsies and treated with chemotherapy followed by surgery, compared to those with low levels of calpain.

“We are passionate about understanding how breast cancer gains the ability to spread around the body, and what makes certain cancers resistant to treatment, so we can improve survival,” the study’s senior author, Professor Stewart Martin with the university’s Translational and Radiation Biology Research group, said in a press release. “The results increase our understanding of this important protein in breast cancer, particularly in poor prognostic groups, which may be the key to unlocking effective ways to target these proteins to improve patient outcomes.”

Calpain proteins are involved in a variety of important cellular functions, including cell signaling, motility, death, and survival. Their abnormal expression and activity have been described in a number of diseases, including Alzheimer’s and cancer. In breast cancer, particularly, the calpain system was shown to be associated with clinical outcomes in patients with early invasive disease.

Researchers investigated whether the expression of calpain in the diagnostic biopsies of women with large but operable breast cancer, who were treated with chemotherapy prior to surgery, was also associated with outcomes for these patients. In total, they examined samples from 68 people treated at the Leeds Teaching Hospitals NHS Trust between 2005 and 2009 for inflammatory and non-inflammatory breast cancer.

Results for the entire patient group showed that calpain levels overall were not associated with breast cancer survival. But in people with non-inflammatory breast cancer, low calpain-2 levels were significantly associated with poorer survival. Similarly, low levels of calpain-1 in people with inflammatory breast cancer were significantly associated with poorer outcomes.

This suggests that determining the levels of calpain in primary biopsies may be important to predicting clinical outcome and determining best treatment. Further studies in larger cohorts are needed, though, to validate these results.