A recent study examined the effectiveness of chemotherapy in two large groups of patients, one with breast cancer and the other with colon cancer. The study found that except for one specific combination treatment, chemotherapy may not prolong life for breast cancer patients over 80 years old.
On the other hand, the study found that chemotherapy remains effective up to the age of 89 for men and women with colon cancer.
Researchers used data from the Surveillance Epidemiology and End Results database covering the time period from 1992 to 2002. SEER is run by the National Cancer Institute and provides cancer statistics on the US population.
The data that was analyzed came from 14,440 women diagnosed with Stage I to IIIA hormone receptor-negative breast cancer and 26,893 men and women diagnosed with Stage III colon cancer. All of the patients were over the age of 65.
The analysis showed that for breast cancer patients, chemotherapy reduced their risk of death from all causes by 30% in patients aged 65 – 69, by 25% in those aged 70 – 74 and by 24% in those aged 75 – 79. Unfortunately, for women over the age of 8-, chemotherapy did not significantly reduce risk of death.
However, there was an exception. A small number of women over the age of 80 who received combination chemotherapy in the form of doxorubicin and cyclophosphamide, there was a 29% reduction in death risk.
When choosing a chemotherapy to treat breast cancer, doctors account for a number of factors which include patient’s age and state of health and characteristics of the cancer, such as stage, hormone-receptor status, HER2 status and lymph node status.
The large sample sizes in the study strengthens evidence suggested by previous smaller clinical trials that have found chemotherapy is not effective for breast cancer patients over the age of 70.
Researchers believe that chemotherapy’s reduced effect on the risk of mortality in older breast cancer patient could be attributed to multiple factors: tumors being less sensitive to chemotherapy; a decrease in dosage as the body gets weaker with age or chemotherapy killing healthy cells in addition to cancer cell.