Cancer survivors from poorer places at higher risk of second cancer

By James Gamble via SWNS

Breast cancer survivors from more deprived areas are at a far higher risk of developing a second cancer, a new study shows.

Researchers found female breast cancer survivors diagnosed under the age of 50 were especially at risk of developing a second cancer.

Women from the most deprived socioeconomic backgrounds were also seen to be over a third more at risk of a second primary cancer than those from the least deprived areas.

The authors of the study, from the University of Cambridge, say their research could help inform estimates on populations more at risk of developing a second cancer.

Breast cancer is the most commonly diagnosed cancer in the UK and one of the most common cancers across the world.

Around 56,000 people in the UK are diagnosed each year, the vast majority of whom (over 99 percent) are women.

Improvements in earlier diagnosis and treatments mean five-year survival rates - the percentage of people alive five years after their initial diagnosis - have been increasing over time and reached 87 percent in England in 2017.

Though it has long been established that survivors of breast cancer are at a higher risk of developing a second primary cancer, up until now the actual risk has remained unclear.

Previously research has suggested that both women and men who survive breast cancer are at a quarter higher risk (24 percent and 27 percent respectively) of a second primary cancer other than breast cancer than the wider population.

Age has also been shown in some studies to be a factor in breast cancer survivors developing secondary cancers.

In their new study, the University of Cambridge team analyzed data from more than 580,000 female and 3,500 male breast cancer survivors diagnosed between 1995 and 2019, using the National Cancer Registration Dataset.

Their results, published in the Lancet Regional Health Europe journal, showed significantly increased risks of cancer in the contralateral - or unaffected - breasts of breast cancer survivors, as well as higher risks of endometrial cancer in women and prostate cancer in men.

Women who survived breast cancer were found to be at double the risk of contralateral breast cancer compared to the general population, and at an 87 percent greater risk of developing endometrial cancer, a 58 percent greater risk of developing myeloid leukemia and a quarter (25 percent) greater risk of developing ovarian cancer.

The age of first diagnosis of breast cancer also appeared to affect the risk of women developing a second cancer, with those diagnosed aged 50 or under at an 86 percent higher risk of developing a second primary cancer than the general population of the same age.

Women diagnosed after 50, in comparison, had a 17 percent increased risk of a second cancer.

One potential explanation offered by the researchers is that a larger number of younger breast cancer survivors could have inherited genetic alterations that increase the risk of multiple cancers.

For example, women with inherited changes to the BRCA1 and BRCA2 genes are at an increased risk of contralateral breast cancer, ovarian and pancreatic cancer.

Strikingly, women from the most socioeconomically deprived backgrounds were more than a third (35 percent) more likely to develop a second primary cancer compared with those from the least deprived backgrounds.

These differences were primarily driven by non-breast cancer risks, particularly for lung, kidney, head and neck, bladder, oesophageal and stomach cancers.

The researchers said this may be because established risk factors for cancer such as smoking, obesity, and alcohol consumption are more common amongst more deprived groups.

Isaac Allen, a first author of the study and a PhD student at the University of Cambridge's Department of Public Health and Primary Care, explained: "It’s important for us to understand to what extent having one type of cancer puts you at risk of a second cancer at a different site.

"The female and male breast cancer survivors whose data we studied were at increased risk of a number of second cancers. Knowing this can help inform conversations with their care teams to look out for signs of potential new cancers.

“This is further evidence of the health inequalities that people from more deprived backgrounds experience.

"We need to fully understand why they are at greater risk of second cancers so that we can intervene and reduce this risk.”

The study, which was funded by Cancer Research UK, also found male breast cancer survivors were around 55 times more likely than the general male population to develop contralateral breast cancer - though the researchers stressed that the risk remained very low.

For example, for every hundred men diagnosed with breast cancer at age 50 or over, around three developed contralateral breast cancer over the next 25 years.

Male breast cancer survivors were also found to be 58 per cent more likely to develop prostate cancer than the general male population.

Professor Antonis Antoniou, the study’s senior author, added: “This is the largest study to date to look at the risk in breast cancer survivors of developing a second cancer.

"We were able to carry this out and calculate more accurate estimates because of the outstanding data sets available to researchers through the NHS.”

Cancer Research UK’s senior cancer intelligence manager, Katrina Brown, stressed the need for further research into the factors driving the differences in secondary cancer risks.

"This study shows us that the risk of second primary cancers is higher in people who have had breast cancer, and this can differ depending on someone’s socioeconomic background," she said.

"But more research is needed to understand what is driving this difference and how to tackle these health inequalities.”