CV Death a Major Competing Risk in Older Women With Early-Stage Breast Cancer

Larry Hand

October 17, 2016

TORONTO, ON — With cardiovascular death an important competing risk for older women with early-stage breast cancer, clinicians should provide adequate preventive cardiovascular care after breast-cancer diagnosis, according to new research[1].

"In a population of women treated for breast cancer, cardiovascular disease is an important contributor to mortality," Dr Husam Abdel-Qadir (University of Toronto, ON) told heartwire from Medscape. "However, we've shown that within a median of approximately 7 years, the contribution of cardiovascular disease to mortality is more prevalent in women over the age of 66 years."

"This allows clinicians and researchers in cardio-oncology to triage their attention more effectively in the women in whom cardiovascular disease is expected to be enough of a competing risk that they will require particular attention while getting treated for breast cancer and subsequent to that," he said.

Abdel-Qadir and colleagues conducted a population-based cohort study involving 98,999 women (median age 60) diagnosed with early-stage breast cancer between April 1, 1998 and March 31, 2012 using the Ontario Cancer Registry. They followed up until patient death or December 31, 2013.

The results were published online October 12, 2016 in JAMA Cardiology.

Almost 38% (37,425) of the women were 66 years old or older, and 6.6% (6559) had prior CVD.

Just over 45% received chemotherapy, and 46.1% received radiotherapy. Of women 66 and older, 29.6% received aromatase inhibitors and 35/6% received tamoxifen.

During a median follow-up of 6.6 years 21.3% (21,123) died, with the median time to death at 4.2 years. Breast cancer was the most common cause (10,550 deaths, 49.9%), while cardiovascular death was infrequent in women younger than 66 without prior CVD, diabetes, or hypertension.

Among women 66 or older, the risk of breast cancer death at 10 years was 11.9% and the risk of cardiovascular death was 7.6%. For women with prior CVD, the risk of breast-cancer death and cardiovascular disease were equal for the first 5 years, then cardiovascular death risk was higher (10-year cumulative incidence 14.6%, 95% CI 13.7%–15.4%).

In women 66 and older who survived 5 years after breast cancer diagnosis, cardiovascular death was more common than breast cancer death at 10 years. Women 66 and older accounted for 89.6% of cardiovascular deaths and 43.9% of breast-cancer deaths.

Women 75 and older were 42 times more likely to die of cardiovascular causes than women younger than 55.

Appropriate care for women with early-stage breast cancer "should involve counseling and preventive interventions that are proportionate to their expected cardiovascular risk," the researchers wrote.

"One take-home message from the study is that cardiovascular disease is a leading contributor to mortality after a diagnosis of breast cancer within the first 10 years after diagnosis," Abdel-Qadir told heartwire .

"Moreover, it is likely to assume more importance with longer follow-up, as over 78% of the cohort was still alive at study end. Thus, cardiovascular preventive therapy should be an important part of the comprehensive care delivered to women with cancer, both during therapy and during the formulation of cancer-survivorship programs," he said.

The Heart and Stroke Foundation of Canada and the Institute for Clinical Evaluative Sciences supported this research. Abdel-Qadir reported being supported by a grant from the Canadian Institutes of Health Research. Disclosures for the coauthors are listed in the article.

Follow Larry Hand on Twitter: @LarryHand16. For more from theheart.org, follow us on Twitter and Facebook.

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