MORTALITY among people with cancer who survive at least 5 years after diagnosis is higher than for the general population, particularly in terms of cardiovascular disease-related mortality, according to research published today by the Medical Journal of Australia.
Researchers led by Professor Bogda Koczwara, medical oncologist and senior staff specialist at the Flinders Medical Centre and Flinders University, analysed South Australian Cancer Registry data for all people diagnosed with cancer during 1990–1999 and alive 5 years after diagnosis, with follow-up to 31 December 2016.
Of 32 646 people with cancer alive 5 years after diagnosis, 17 268 deaths were recorded (53% of patients; mean age, 80.6 years; SD, 11.4 years): 7845 were attributed to cancer (45% of deaths) and 9423 were attributed to non-cancer causes (55%). Ischaemic heart disease was the leading cause of death (2393 deaths), followed by prostate cancer (1424), cerebrovascular disease (1175), and breast cancer (1118). The overall standardised mortality ratio (adjusted for age, sex, and year of diagnosis) was 1.24 (95% CI, 1.22–1.25). The cumulative number of cardiovascular deaths exceeded that of cancer cause-specific deaths from 13 years after cancer diagnosis.
“Overall, 26.7% of all deaths and 56.1% of non-cancer deaths were attributed to cardiovascular diseases,” Koczwara and colleagues wrote.
“Our findings may partly reflect the high prevalence of and mortality from cardiovascular disease in Australia, but we also found that cardiovascular mortality was higher than in the general population.
“Our findings suggest an interaction between cancer or its treatment and cardiovascular risk factors. The interaction may reflect a biological phenomenon (such as a direct toxic effect of anti-cancer treatment on the heart or vascular system), or it may reflect lack of prioritisation of cardiovascular disease by patients or health care focused on treating cancer,” they wrote.
“It is notable that cardiac failure was a relatively infrequent cause of death (2.2% of all deaths), suggesting that cancer treatment toxicity, which tends to cause cardiac failure, may lead to earlier mortality, which would not have been identified in this study of individuals who survived at least 5 years after diagnosis, with later mortality from cardiovascular disease driven more by existing risk factors and background population risk.”
The authors concluded that cancer survivorship care should include early recognition and management of risk factors for cardiovascular disease.
“Cancer control systems should incorporate monitoring of long term survivorship outcomes, including non-cancer-related mortality, and manage risk factors for premature death from non-cancer causes.”
- Cate Swannell