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A LEADING cancer specialist and researcher says new research showing cancer survivors are more likely to be diagnosed with chronic illnesses than people who have never had cancer highlights the need to include GPs and geriatricians in cancer teams.
Professor Fran Boyle, director of the Patricia Ritchie Centre for Cancer Care and Research at the Mater Hospital in Sydney and professor of medical oncology at Sydney Medical School, said common underlying risk factors such as smoking, obesity, sedentary lifestyle and diet were likely to explain the results of the study.
The research, published online today by the MJA, compared 2103 people with a previous cancer diagnosis with 4185 age- and sex-matched controls, finding those with a history of cancer were more likely to have chronic conditions such as diabetes and cardiovascular disease, with men at greater risk. (1)
The study authors said their findings highlighted the importance of managing chronic illness after a cancer diagnosis.
They found men with a history of cancer were more likely to have ever had cardiovascular disease (P < 0.001), high blood pressure (P = 0.001), high cholesterol (P < 0.001) or diabetes (P = 0.04) than controls, despite similar body mass index and levels of physical activity between the two groups. The findings remained significant after adjusting for socioeconomic status, with the exception of hypertension.
For women, the higher risks of chronic diseases in the cancer group were not significant after adjusting for socioeconomic status.
The study authors, from Flinders University, Adelaide, postulated a number of possible causes.
“It is possible that chronic illness itself may predispose to cancer”, they wrote.
“Increased risk of cancer has been reported in patients with diabetes, and cardiovascular disease and osteoporosis share the common aetiological factors of inactivity and obesity with cancer.”
Alternatively, “cancer or cancer treatment may predispose to chronic disease”, they wrote, saying “endothelial dysfunction, platelet activation and upregulation of prothrombotic factors as a result of anticancer therapy have been postulated, but other mechanisms yet to be defined, could be involved”.
The results might also reflect underdiagnosis of chronic diseases among controls, with the authors noting that “diagnosis and treatment of cancer brings men under the surveillance of health and medical services”.
More than a third of cancer patients in the study reported a history of skin cancer; however, removing these patients from the analysis did not alter the results.
The study was limited by its reliance on self-reported data from telephone interviews.
Professor Boyle told MJA InSight the upside of the study results was that for cancer specialists “this might be a ‘teachable moment’ for patients to get their health more generally sorted out”.
“The downside is that chronic diseases limit delivery of cancer treatment so may lead to poor outcomes which, sadly, is not addressed in this work.”
Professor Moyez Jiwa, professor of health innovation at Curtin University, Perth, whose research focuses on improving the diagnosis and management of chronic conditions in primary care, told MJA InSight that currently there wasn’t a “proactive approach” to screening cancer survivors for unmet need in primary care.
“We need to offer patients treated for cancer a regular follow-up appointment and to screen them for other morbidities as well as unmet need related to the long-term side effects of cancer treatment … The issue is that Medicare does not fund the required service”, he said.
He said further research should consider the geographical distribution of the cancer cases relative to the controls.
“The neighbourhood in which we live has a profound impact on our choices and our health by access to services, exposure to poor sources of nutrition, less scope for exercise, employment status, job type and the social and cultural influence on our health.”
Thanks for this useful report, whose quallty was reduced by the pointless inclusion of p values that really don’t ell us anything useful. Knowing that “men with a history of cancer were more likely to have ever had cardiovascular disease (P < 0.001)” tells us only that if the null hypothesis is true (that is, that the prevalence of cardiovascular disease is the same in men with a history of cancer as in men who have never been diagnosed with cancer), the likelihood of obtaining a result as extreme or more extreme than that found in the study is less than 1 in 1 000.
This use of a p value by itsef does not convey much to the reader about what the study found. What we really want to know, that would really tell us something useful would be that (for example) 67% of men with a history of cancer had had cardiovascular disease, while ony 34% of men without cancer had had cardiovascular disease, perhaps with some confidence intervals.