Cancer survivors have high rates of premature death from cardiovascular disease, highlighting the need to focus on risk factor management after successful cancer treatment, an Australian study shows.
Dr Bogda Koczwara, a medical oncologist at Flinders University of South Australia, presented findings at COSA 2020 showing that long term survivors from cancer have a higher standardised mortality rate (SMR) compared to the general population, driven mostly by cardiovascular mortality.
Excess cardiovascular deaths were more common among male cancer survivors and more commonly seen for certain cancer types such as prostate and lung cancer.
The retrospective cohort study used the SA cancer registry to analyse cause of death for 32,646 people diagnosed with cancer between 1990 and 1999 who survived five years after their diagnosis.
With a median follow-up of 17 years there were 17,268 (53%) deaths, with about half attributed to cancer and half to to non-cancer causes. Among cancer survivors the leading causes of death were ischaemic heart disease, followed by prostate cancer, cerebrovascular disease, and breast cancer.
Compared to the general population, the standardised mortality ratio for cancer survivors was 1.24, with Hazard Ratios (HR) higher for males than females (1.38 vs 1.11). A similar pattern was seen for cardiovascular mortality rates, which were higher for males than females (1.69 vs 1.17).
Cardiovascular mortality was particularly high in individuals who has survived lung cancer (HR 3.27) and prostate cancer (HR 1.55).
Dr Koczwara said it was surprising to see low rates of cardiac failure (2%) in the cohort because traditional teaching in cardio-oncology has been that this is the main condition to focus on as a result of cancer treatment.
She said the excess mortality rates seen in cancer survivors showed the need for oncology professionals to look beyond the good outcomes they are achieving for patients with cancer treatment.
“Our study highlights that as cancer professionals we hold not just the cancer outcomes but also the outcomes for other chronic outcomes in our hands. Certainly oncology professionals needs to start upskilling on recognising [cardiovascular] risk factors.“
“This [excess mortality] may be biologic, reflecting common aetiological pathways, or the effect of the cancer treatment – or it may reflect health service issues where the healthcare providers and patients prioritise cancer above cardiovascular disease,” Dr Koczwara told the meeting.
She said there is a need to develop accurate cardiovascular risk tools for cancer survivors, as has been done for Hodgkins disease, and to develop and test management strategies and pathways for cardiovascular disease as part of cancer survivorship care
“But I think the question really is what is the appropriate management for the appropriate levels of risk. There are some cancers such as skin cancer where the incremental risk is modest and patients may be well managed within the normal recommendations for the general population – and there are other cancers where the detrimental effect from comorbidities on premature death is substantial – be it prostate cancer or lung cancer – and we really need to prioritise and test effective interventions for those patients.”