A German study has found that young breast cancer patients, those 35 years and younger, tend to benefit more from neoadjuvant chemotherapy. The results are presented today at the annual San Antonio Breast Cancer Symposium (SABCS) in Texas. Sibylle Loibl, MD, PhD, an associate professor at the University of Frankfurt in Germany, presented the results that pathological complete responses (pCRs) were significantly higher following neoadjuvant treatment for young women, 23.6% compared to 15.7% among women older than 35 (P < .0001).
Women diagnosed with breast cancer at a younger age tend to have more aggressive breast cancer, but the prevalence of disease in this age group is much lower compared to older women. Approximately 5% of breast cancers occur in women under 40, according to the American Cancer Society. Breast cancer is the leading cause of cancer death among women between the ages of 20 and 59.
Loibl and colleagues compiled and analyzed the data from eight German studies that included almost 9,000 breast cancer patients. A large cohort of patients 35 or younger were included—a total of 704 women. All patients were treated with neoadjuvant chemotherapy and had operable or locally advanced breast cancer that was not metastatic. The young women cohort had a greater proportion of triple-negative breast cases compared to the older age cohort—26% compared to 19%, respectively. Young breast cancer patients also had a lower frequency of luminal A–type breast cancer compared to patients over 35—21% compared to 27%, respectively.
The analysis is retrospective and compared outcomes based on age group, but could not draw conclusions about the type of chemotherapy that may be best for patient subsets nor if the patients’ outcome would have been similar without chemotherapy.
The difference in pCRs was fully explained by those young women who had triple-negative breast cancer: 45% of young women with triple negative breast cancer achieved a pCR compared to 31% of older women with triple-negative breast cancer. Age was found to be an independent predictor of a pCR only for triple-negative breast cancer patients. Overall, hormone receptor status and grade of disease were independent predictors of pCR for young compared to older women. Young patients who did not achieve a pCR had a worse disease-free survival (P = .001).
Among women with luminal A–type breast cancer, age could predict disease-free survival, but pCR did not predict disease-free survival. The worst prognosis among luminal A patients was for those women who were younger than 35 but did not achieve a pCR, while the best prognosis was for those under 35 who did achieve a pCR.
“It can be hypothesized that the very young patients with luminal A tumors benefit from a pCR, whereas overall pCR is not a predictor in the luminal A subgroup,” stated the authors.
“Age reflecting the hormonal milieu seems to be a factor influencing the response to chemotherapy,” said Loibl. “The young women with a pCR have a better outcome even with luminal-like breast cancers whereas older women with a luminal tumor do not derive the same benefit.”
Loibl said she was not surprised by these results as single studies have previously shown age as a factor affecting response to neoadjuvant chemotherapy. “Age is an independent predictor for chemotherapy response in addition to the other tumor characteristics,” said Loibl.
The results can be extended to other countries that use similar chemotherapies as those given to patients in these Germany studies, according to Loibl.
Loibl believes this study may impact whether oncologists decide to suggest neoadjuvant chemotherapy for patients 35 and under.
The study researchers are currently planning a prospective follow-up study that will collect breast cancer patient tumor samples and compare neoadjuvant to adjuvant treatment.