New results from breast cancer clinical trial show non-breast cancer related causes account for most deaths

01 February 2008

Dr Judith-Anne ChapmanFebruary 2008 - New findings from a landmark breast cancer clinical trial involving the drug letrozole show that, in this group of patients, women were more likely to die from non-breast cancer-related causes than from breast cancer-related causes.

The research team found that non-breast cancer related causes accounted for 60% of deaths. The top causes of death included: cardiovascular disease including stroke (15%), other malignancies (15%), infection (6%), multiple causes (5%), and non-cardiovascular organ failure (4%). The results were particularly striking for older women. Among women aged 70 years or older, non-breast cancer-related causes accounted for 72% of deaths. The new results are published in the February 12 issue of the Journal of the National Cancer Institute.

The original study results were first published in The New England Journal of Medicine in October 2003 and involved 5,170 post-menopausal breast cancer survivors with a median age of 62 years (range 32 to 94 years). It determined that women who took letrozole for up to five years following 5 years of tamoxifen therapy experienced a significantly reduced risk of cancer recurrence. The clinical trial was coordinated by the NCIC Clinical Trials group and was funded in part by the Canadian Cancer Society.

Routine use of mammography and improved treatment for breast cancer will mean that more women will survive breast cancer at older ages, at which time they might have a higher risk of death from causes other than breast cancer, says Dr Judith-Anne Chapman, lead author of the study.

“The study findings show that we are successfully treating women with breast cancer. However, the study also underscores the need to pay more attention especially to older women and the potential for death from other causes,” Dr Chapman says.

Breast cancer is the most common cancer among Canadian women. In 2007, an estimated 22,300 women will be diagnosed with breast cancer and 5,300 will die of it.