By Lisa Rapaport

(Reuters Health) – White women with breast cancer are more likely to complete their prescribed chemotherapy regimen than women of color, a U.S. study suggests.

Just 50 percent of non-white women in the study finished all of their prescribed treatments, compared with 76 percent of white women, researchers found.

The study included 124 women prescribed so-called neoadjuvant chemotherapy, treatment often recommended before surgery for patients with larger cancers because it can shrink tumors and allow for less extensive operations. Overall, 92 women, or 74 percent, completed their neoadjuvant chemotherapy.

After accounting for factors like age, insurance status and tumor size, white women were more than three times as likely to finish neoadjuvant chemotherapy as black, Hispanic and Asian women.

“There is no clear explanation available for how race affects completion of neoadjuvant chemotherapy,” said senior researcher Dr. Shayna Lefrak Showalter of the University of Virginia School of Medicine in Charlottesville.

She and her colleagues note in the journal Surgery that racial disparities in outcomes for Americans with breast cancer and other malignancies have been attributed to multiple factors. These include different tumor biology, less frequent screening, less aggressive treatment and failure to seek medical care and follow-up treatment.

In this study, “For both white and non-white patients, the most common reason given for stopping treatment early was drug toxicity,” Showalter said by email. “In order for patients to receive maximum benefit from therapy, it is important for them to complete the prescribed dose.”

More than half of the women who stopped treatment early cited side effects, most often neurological problems or pain for women of color and gastrointestinal issues for white women. Some patients also discontinued treatment because of cancer progression, psychological or social issues, or personal beliefs.

Non-white patients were more likely to have larger tumors before chemotherapy and more likely to have insurance through government health programs like Medicaid, but these factors didn’t appear to influence the likelihood of completing treatment.

There also wasn’t a difference in the types of treatment regimens prescribed to white and non-white patients that could help explain the likelihood of completing neoadjuvant chemotherapy.

One goal of neoadjuvant treatment is to increase the chance that women will be able to have a lumpectomy, or breast-conserving surgery, instead of a mastectomy that removes the entire breast. Completion of neoadjuvant treatment didn’t appear to influence the chance that women would get a lumpectomy, however.

Another goal is to make it more likely that women will experience what’s known as a pathologic complete response (pCR), when no tumor remains after neoadjuvant chemotherapy, because this is linked to better survival odds. But this outcome also didn’t appear to be influenced by whether women finished all of their prescribed treatments.

“Our main concern would be that incomplete neoadjuvant chemotherapy could lead to lower rates of pCR or breast conserving surgery (i.e. lumpectomy),” said Erica Warner, a researcher at Harvard Medical School and Massachusetts General Hospital in Boston who wasn’t involved in the study.

“This study did not find differences in breast surgery or pCR between those that completed neoadjuvant chemotherapy and those that didn’t,” Warner said by email.

The study wasn’t a controlled experiment designed to prove whether or why race might influence the odds of completing neoadjuvant chemotherapy. It was also too small and brief to shed any light on survival odds, and included only 38 non-white patients.

“The numbers are too small to draw any conclusions, and most patients who stopped treatment early stopped for toxicity,” said Dr. Rachel Freedman, a disparities researcher at Dana-Farber Cancer Institute in Boston, who wasn’t involved in the study.

“For me, this study points out how we need to better address toxicity in patients rather than focusing on disparities,” Freedman said by email.

SOURCE: Surgery, online May 3, 2018.