Research, published in The British Medical Journalnoted that for women who have undergone breast cancer treatment, the risk of a second primary cancer – which means cancer from breasts – has only increased by around 2% compared to the general population.
But the relatively low increase in risk should be “very reassuring” for women with a history of breast cancer, explains Dr. Mouabbi, who was not involved in the study.
Risk of a different type of cancer only marginally higher for breast cancer survivors
Researchers analyzed data from the British National Cancer Recording and Analysis Service, identifying more than 475,000 women with breast cancer as the first invasive cancer from 1993 to 2016. From these women, researchers followed 86% for at least five years.
About 65,000 have developed a second primary cancer, mainly in the uterus or lungs. It is the equivalent of 13.6% of participants – 2.1% more than what is expected for the general population.
Another 5.6% developed breast cancer in the opposite breast (called a contralateral breast cancer) – about 3% more than the general population. This risk was higher in younger women, the study noted.
“Our study confirms that the risks of new cancers are higher for breast cancer survivors than for other women of the general population,” said the main author David Dodwell, MD, main clinical researcher in the population of the population and clinical oncologist consultant at the University of Oxford in England.
“However, these additional risks are low compared to the risks of recurrence and death of breast cancer in the vast majority of women diagnosed with early invasive breast cancer, despite substantial improvements in the treatment of early breast cancer.”
How the types of treatment affect the risk of secondary cancer
The study focused on women who have undergone breast conservation surgery or mastectomy as a first treatment. Researchers have gathered women according to the type of adjuvant therapy they obtained (or additional treatment after surgery) to examine the links between the type of treatment and the risk of secondary cancers.
They found that radiotherapy was associated with higher rates of contralateral breast and lung cancer. Endocrine treatment (hormonal) was linked to an increased risk of uterine cancer, but a decrease in the risk of cancer of the contralateral breast. Chemotherapy was linked to an increased risk of acute leukemia.
Although it may seem alarming, it is important to note that breast cancer treatments have progressed today far beyond those available in the 90s and even a decade ago, explains Hope Rugo, MD, head of the Division of Medical Oncology of the Sein in City of Hope in Duarte, California, which was not involved in the study.
These improved treatments could reduce the risk of secondary cancer, she adds.
For example, in the past, doctors have delivered radiation directly to the chest where he often reached the lungs, who are behind the breasts, explains Dr. Rugo. Today, they deliver lateral radiation and isolate the breast to protect the lungs.
Even if certain cancer treatments can have side effects, Mouabbi says that all small risks prevail over the advantages.
“It is important to note that treatment is what prevents other cancers from arising,” he says.
The study has limits
Researchers noted that certain cancer register data were incomplete in certain areas, such as adjuvant treatments. The data analyzed also lacked information on the family history of the participants, all genetic predispositions to cancer and lifestyle factors such as smoking.
Less than 5% of participants have been recorded as non -white and men have not been included, so the results may not be generalizable to other groups.
Because the study was observational – which means that there was no control group or intervention – the results do not prove that the adjuvant therapies caused secondary cancers, only that there is a link.
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