After cancer: Relapse is the biggest fear, but not the only risk

The chances of surviving a brush with cancer have increased substantially in the last decade. A combination of earlier diagnosis, better access to treatment and newer innovative treatments have all helped. As a result, there are more than 165,000 people living with and beyond cancer in Ireland today.

It does mean, however, that some people who are diagnosed with cancer have a history of a previous malignancy. And most of the prior cancers will have been diagnosed in a different site in the body.

According to recent US research, about a quarter of patients with cancer aged 65 years and older and about one in 10 younger adults had had a previous malignancy. The prevalence ranged from 4 per cent to 37 per cent in a cohort of more than 740,000 patients.

For the patient with a history of cancer, the fear of a recurrence of the same cancer recedes with time. But I suspect the possibility of a second – different – type of cancer is not something that is on most people’s radar.

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The recent research found that, among younger patients, the most prevalent prior cancers included leukaemia (25 per cent) cancer of the rectum (18 per cent); cancer of the cervix and other female genital organs (15 per cent); and a similar percentage of lung and other respiratory cancers.

For older patients, the most prevalent previous cancers were skin melanoma and leukaemia (both 37 per cent), followed by bone and bladder and other urinary organs.

How can we explain this data? Firstly, they make sense in that diagnosis of a first cancer is frequently associated with diagnosis of a second cancer because of shared underlying risk factors – such as tobacco use, obesity, or exposure to a known carcinogen like the human papillomavirus. In addition, the treatment for the previous cancer can lead to the development of a subsequent second cancer.

Earlier this month, the American Heart Association warned that some breast cancer survivors, who have been treated with common chemotherapies, are at increased risk for heart failure and other cardiovascular diseases. And it called on oncologists to weigh the benefits of those treatments against the heart risks they pose.

It has been known for years that some breast cancer drugs can weaken the heart muscle, causing heart failure. An older class of cancer drugs called anthracyclines, which includes doxorubicin, can kill cardiomyocytes, which make up the heart muscle, especially in older women or those with pre-existing heart disease. Taxanes, such as paclitaxel, can cause an abnormally slow heart rhythm.

Side effects

All cancer patients face indirect side effects from the disease. They have a significantly increased risk of venous thromboembolism (VTE) – an umbrella term for two conditions, deep vein thrombosis (DVT) and pulmonary embolism (PE). DVT is a disease caused by a blood clot found in deep veins, usually within the lower leg, thigh or pelvis. PE occurs when part of a clot detaches and lodges in the pulmonary arteries, which can be fatal.

Current guidelines recommend daily injections of heparin for at least six months as the standard of care in cancer patients, but adherence to this treatment is poor. However, there was good news in the Hokusai Cancer study published before Christmas which showed a lower rate of recurrent VTE with the novel oral anticoagulant drug edoxaban compared with heparin over a one-year study period.

Meanwhile, a separate study has outlined another challenge facing cancer patients. About one-fifth of patients experienced post-traumatic stress disorder (PTSD) several months after diagnosis, and some six per cent of patients continued to live with PTSD four years later. Researchers blamed the pressure many people with cancer feel to adopt a “warrior mentality”, and to remain positive to stand a better chance of beating their cancer.

While no one would want to go back to the days of the Big C being an almost certain killer, living beyond cancer has its own challenges.

mhouston@irishtimes.com