Heart disease and stroke kill over 1 in 10 cancer patients in US, those with breast, prostate and bladder cancer at much higher risk
More than one in 10 cancer patients in the US do not die from their cancer but from heart disease and strokes. Among the 3,234,256 cancer patients who were part of a new study, 38% or 1,228,328 died from cancer, and 11.3% or 365,689 died from cardiovascular diseases, according to researchers from Penn State College of Medicine and Penn State Cancer Institute, Pennsylvania, US.
According to the analysis, the risk is higher for certain type of cancers like breast, prostate, endometrial, and thyroid, with around half dying from cardiovascular disease (CVD).
The researchers examined deaths from CVD among patients with 28 types of cancer with over 40 years of data. They found that among the deaths from cardiovascular diseases, 76.3% were due to heart disease. The analysis also shows that the risk of dying from CVD was highest in the first year after a cancer diagnosis and among patients younger than 35 years.
"Cancer survivors with cancer of the breast, larynx, skin, Hodgkin lymphoma, thyroid, testis, prostate, endometrium, bladder, vulva, and penis, are about as likely to die of cardiovascular diseases as they are to die of their initial cancer. The risk of death from cardiovascular diseases is several times that of the general population in the first year of diagnosis; sometimes, this risk decreases, but for most, this risk increases as survivors are followed for 10 years or more," says Dr. Kathleen Sturgeon, an assistant professor in public health sciences, and affiliated to both Penn State College of Medicine and Penn State Cancer Institute.
Dr. Sturgeon says, "Increasing awareness of this risk may spur cancer survivors to implement healthy lifestyle behaviors that not only decrease their risk of cardiovascular disease but also the risk of cancer recurrence," says Dr. Kathleen Sturgeon, an assistant professor in public health sciences, and affiliated to both Penn State College of Medicine and Penn State Cancer Institute.
According to Dr. Nicholas Zaorsky, a radiation oncologist, also affiliated with both Penn State College of Medicine and Penn State Cancer Institute, the reason why cancer patients are more at risk of dying from cardiovascular disease within the first year of diagnosis might be because when they entered the hospital system, other illnesses and problems, such as heart disease, lung dysfunction, and kidney failure were also detected. It could also be explained by the aggressive treatment that follows a cancer diagnosis.
"Clinicians need to be aware that the majority of cardiovascular disease deaths occur in patients diagnosed with breast, prostate, or bladder cancer. Thus, clinics that aim to open "cardio-oncology" centers should likely focus on the inclusion of these sites, followed by the other sites listed above.
Additionally, primary care physicians and cardiologists may seek to control cardiovascular diseases more aggressively in cancer survivors," says Dr. Zaorsky.
The researchers compared the US general population, with over 3.2 million US patients, who had been diagnosed with cancer between 1973 and 2012.
"Heart disease and cancer are the leading causes of mortality, both in the US and worldwide. During 2015, in the US, 633,842 deaths were due to heart disease, while 595,930 deaths were due to cancer.
Worldwide, in 2015, 17.7 million deaths were due to cardiovascular diseases (CVDs), while 8.8 million were due to cancer. With recent progress in screening, diagnosis, and treatment of many cancers, the population of cancer survivors is steadily increasing. It is expected that by 2040, the number of Americans with a history of cancer will increase to more than 26 million," says the study published in the European Heart Journal.
The experts used the information in the Surveillance, Epidemiology, and End Results (SEER) database to examine deaths from CVD. This includes heart disease, high blood pressure, cerebrovascular disease, blocked arteries, and damage to the aorta - the main artery carrying blood from the heart to the rest of the body.
In the representative sample, 49.3% of cancer patients died from either their cancer or from CVD during the study period.
The researchers found that patients who were more likely to die from cancer than from cardiovascular diseases were those with the most aggressive and hard-to-treat cancers, such as cancer of the lung, liver, brain, stomach, gallbladder, pancreas, esophagus, ovary and multiple myeloma.
According to the analysis, the majority of cardiovascular deaths occurred in patients with cancers of the breast -- a total of 60,409 patients and prostate with 84,534 patients -- as these are among the most common cancers to be diagnosed. In 2012, 61% of all cancer patients who died from CVD were diagnosed with breast, prostate, or bladder cancer, says the team.
"Urinary bladder cancer patients have the highest risk of dying from a CVD with 19.4% of bladder cancer patients having died from CVD. The following cancer sites also displayed a higher than average (11.3%) risk for death from CVD in cancer patients: larynx (17.3%), prostate (16.6%), corpus uteri (15.6%), colorectal (13.7%), and breast (11.7%)," the findings state.
"The majority of deaths (absolute numbers) from CVD occur in patients diagnosed with breast, prostate, or bladder cancer. Prostate and breast cancer patients have the largest absolute number of patients who have died of CVDs between 1973 and 2012, and therefore, make up the largest percent (49.2%) of all cancer patients among the 28 cancer sites who have died from cardiovascular causes," says the study.
"These findings show that a large proportion of certain cancer patients will die of cardiovascular disease, including heart disease, stroke, aneurysm, high blood pressure, and damage to blood vessels. We also found that among survivors with any type of cancer diagnosed before the age of 55 years, the risk of cardiovascular death was more than ten-fold greater than in the general population," says Dr. Sturgeon
The researchers hope their study findings will increase awareness in patients, primary care physicians, oncologists, and cardiologists as to the risk of cardiovascular disease among cancer patients. They hope this will lead to earlier, more aggressive, and better coordinated cardiovascular care.
In an accompanying editorial, Dr. Jörg Herrmann, a cardiologist at the Mayo Clinic, Rochester, Minnesota, states that the current study confirms that cancer patients have, on average, two to six times higher CVD mortality risk than the general population.
"This is a key message that every cardiologist needs to hear. Secondly, the CVD mortality risk is evident throughout the continuum of cancer care and entails an acute phase (early risk) and a chronic phase (late risk). In view of such grave and persistent consequences, a reactive management approach that comes into play solely when clinical presentations and complications arise is no longer in order. Rather, one would advocate for a proactive approach that starts before any cancer therapy is given and continues for a lifetime thereafter. Thirdly, even with the best possible cardio-oncology care, no difference in population-based outcomes may be achieved in patients with relentless malignancies, while for others, it is of increasing significance," writes Dr. Herrmann.