In a first-of-its-kind study, Dutch researchers have found women who received a once-common chemotherapy regimen known as CMF between 1976 and 1995 score lower on tests that gauge memory, word learning and information processing than those with no history of cancer.
The study, published online in the Journal of Clinical Oncology, noted CMF -- a combination treatment including the drugs cyclophosphamide, methotrexate, and 5-fluorouracil -- is no longer the standard of care for breast cancer.
But many breast cancer survivors who received it 20 or more years ago may be experiencing subtle but significant cognitive problems with learning and memory.
"To our knowledge, this is the first study to suggest that subtle cognitive deficits may be among the long-term effects of chemotherapy, especially of the earlier regimens,” said lead author Sanne B. Schagen, with the Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital in Amsterdam.
"Our findings do not suggest that breast cancer survivors treated with CMF chemotherapy need to be monitored more closely for cognitive difficulties,” Schage added. “But if breast cancer patients experience cognitive problems, information about the possible long-term effects of their breast cancer treatment may help to guide referral to appropriate support services."
Past studies have shown chemotherapy can cause short-term forgetfulness or problems processing information, which can last five to 10 years. But the new study -- based on tests involving 196 women who received CMF chemotherapy in the 1970s, 1980s and 1990s -- finds those problems can be longer-lasting.
CMF chemotherapy was the standard of care for breast cancer worldwide from the 1970s through the 1990s and was received by thousands of women. Today it has been replaced by anthracycline-based adjuvant regimens but many women who received the regimen in the past are still alive. In addition, cyclophosphamide and 5-fluorouracil are still commonly incorporated in modern chemotherapeutic regimens for breast cancer.