Patients in the early stages of breast cancer who undergo radiation treatments on the left side of their body in a facing-up position are at higher risk of developing heart disease. This is according to a research letter published in JAMA Internal Medicine.
Researchers from the Columbia University Medical Center in New York say that previous research has suggested a link between breast cancer radiation and long-term cardiovascular-related deaths.
Earlier this year, Medical News Today reported on a study published in the New England Journal of Medicine suggesting that breast cancer patients who undergo radiation therapy are at a slightly increased risk of developing heart disease within 5 years of treatment.
For this most recent study, the researchers analyzed 48 patients with stage 0 breast cancer - the earliest form of the disease - up to stage IIA breast cancer. This is a stage of breast cancer in which no tumors are found, but cancer is present in 1 to 3 axillary lymph nodes.
All patients were treated after 2005 at the New York University Department of Radiation Oncology, and the patients' cardiac risks were calculated over a 20-year period following radiotherapy. According to the researchers, this is the estimated mean life expectancy following early stage breast cancer.
Body side and position determines risk
The researchers calculated the link between radiotherapy and heart disease by taking the following factors into consideration:
- Mean cardiac radiation dose
- Cardiac risk of each patient (smoking, cholesterol and hypertension)
- Side of the body that received radiation
- Body position
- Coronary events induced by radiation therapy.
The study findings revealed that the women who had the highest baseline cardiac risk, who received radiation therapy on the left side of their body while in a supine position - lying down with their head facing up - had the highest risk of developing heart disease.
Women who had low cardiac risk at the baseline of the study, who received radiation therapy on the right side of their body demonstrated the lowest risk of heart disease.
The researchers found that patients who received radiation therapy on the left side of their body while in the prone position - lying down and facing down - had reduced radiation dosage and reduced cardiac risk.
Body positioning had little effect on cardiac risk on right-sided therapy, the researchers note, as the heart is always out of the area of radiation.
Lifestyle modification 'could reduce risk'
The researchers conclude that breast cancer patients undergoing radiation therapy could reduce their risk of heart disease by reducing other cardiovascular risk factors:
"Because the effects of radiation exposure on cardiac disease risk seem to be multiplicative, the highest absolute radiation exposure risks correspond to the highest baseline cardiac risk.
Consequently, radiotherapy-induced risks of major coronary events are likely to be reduced in these patients by targeting baseline cardiac risk factors (cholesterol, smoking, hypertension), by lifestyle modification, and/or by pharmacological treatment."
Medical News Today recently reported on a study showing that a new imaging technique tested on mice can detect subtypes of breast cancer and early treatment response.