Study finds increased risk of secondary cancer in breast cancer survivors

Breast cancer survivors are at significantly higher risk of developing secondary tumors, including endometrial and ovarian cancer in women and prostate cancer in men. This became known thanks to a new study based on data from almost 600 thousand patients in England.

For the first time, the study shows that this risk is higher in people living in areas with low socioeconomic levels.

Breast cancer is the most commonly diagnosed type of cancer. Every year, about 2.3 million cases of breast cancer are registered worldwide, the vast majority of which (more than 99%) occur in women. Improvements in early diagnosis and treatment are leading to an increase in five-year survival, reaching 87% by 2017 in England.

People who survive breast cancer are at risk of developing second primary tumors, but until now the exact level of this risk was unclear. Previously published studies suggested that women and men breast cancer survivors were 24% and 27% more likely to develop a second non-breast primary tumor, respectively, compared with the general population. It has also been suggested that the risk of developing secondary tumors depends on the age at which breast cancer is diagnosed.

To get more accurate estimates, a team of researchers from the University of Cambridge analyzed data from more than 580,000 women and more than 3,500 men breast cancer survivors who were diagnosed between 1995 and 2019. The results of their analysis were published in the journal The Lancet Regional Health-Europe.

The study's first author, Isaac Allen, from the Department of Community Health and Primary Care at the University of Cambridge, said: "It is important to understand the extent to which having one type of cancer increases the risk of developing another type of cancer elsewhere. Women and men cancer survivors breasts, had an increased risk of developing several secondary tumors. This knowledge can help discuss with their doctors the need to monitor for signs of possible new tumors."

Researchers found a significant increase in the risk of developing cancer in the contralateral (that is, unaffected) breast, as well as endometrial cancer in women and prostate cancer in men. Women who survived breast cancer had twice the risk of developing contralateral breast cancer compared with the general population, as well as an 87% higher risk of endometrial cancer, a 58% higher risk of myeloid leukemia, and a 25% higher risk of ovarian cancer. p>

Age at diagnosis also played a role. Women diagnosed with breast cancer before age 50 had an 86% greater risk of developing a second primary compared with the general population of the same age, while women diagnosed after age 50 had a 17% greater risk of developing a second primary tumor than the general population of the same age. Higher. One possible explanation is that more young breast cancer survivors may have inherited genetic changes that increase the risk of developing multiple types of cancer. For example, women with inherited changes in the BRCA1 and BRCA2 genes have an increased risk of developing contralateral breast cancer, as well as ovarian and pancreatic cancer.

Women from the most socioeconomically disadvantaged backgrounds had a 35% greater risk of developing second primary tumors compared to women from the least disadvantaged backgrounds. These differences are mainly explained by risks not associated with breast cancer, especially cancers of the lung, kidney, head and neck, bladder, esophagus and stomach. This may be because smoking, obesity and alcohol consumption - established risk factors for these cancers - are more common among more disadvantaged groups.

Allen, a PhD student at Clare Hall, added: "This is further evidence of the health inequalities faced by people from more disadvantaged backgrounds. We need to fully understand why they are at higher risk of developing secondary tumors so we can intervene to reduce this." risk."

Male breast cancer survivors had a 55-fold greater risk of developing contralateral breast cancer compared with the general male population, although the researchers stressed that individual risk was still low. For example, of every 100 men diagnosed with breast cancer at age 50 or older, about three developed contralateral breast cancer within 25 years. Men who survived breast cancer also had a 58% greater risk of developing prostate cancer compared to the general male population.

Professor Antonis Antoniou, from the Department of Public Health and Primary Care at the University of Cambridge, senior author of the study, said: "This is the largest study to date looking at the risk of developing secondary tumors in breast cancer survivors. We were able to carry out this study and obtain more accurate results." estimates thanks to the outstanding datasets available to researchers through the National Health Service (NHS)."

Cancer Research UK's senior cancer information manager, Katrina Brown, said: "This study shows that the risk of developing second primary tumors is higher in breast cancer survivors, and this risk may vary depending on a person's socioeconomic status. But more research is needed to understand what causes this difference and how to combat these health care disparities."