A study of seven Caribbean countries has shown that an average of one in seven Caribbean-born people on those islands who have been diagnosed with breast or ovarian cancer carry at least one inherited gene mutation.
Of the seven territories – Jamaica, Trinidad and Tobago, Cayman, Bahamas, Barbados, Dominica and Haiti – Cayman had the second-lowest rate of hereditary breast and ovarian cancer at 6.3%, after Jamaica, which had 4.9%. The Bahamas had the highest proportion, with 23%, with Barbados at 18%, Trinidad and Tobago at 12%, Dominica at 8.8% and Haiti at 6.7%.
Oncologist Dr. Judith Hurley, who is a researcher at the Sylvester Comprehensive Cancer Centre at the University of Miami Miller School of Medicine, has been studying racial disparities in breast cancer rates since 2002. She was prompted to carry out the study after noticing that many of her Bahamian breast cancer patients were unusually young. She and fellow researcher Dr. Sophia George joined forces with other colleagues from Sylvester, the University of Toronto, and the Bahamas to try to figure out why.
They found that more than a quarter of the women they studied had mutations in two genes, BRCA1 and BRCA2. By comparison, these mutations make up less than 5% of US breast cancer cases. They also determined that the average age of breast cancer onset in Bahamian women was 42 – about 20 years younger than for American women.
The team’s research then expanded to six other English- and Creole-speaking Caribbean islands, including Cayman.
Their findings, titled ‘Gene Sequencing for Pathogenic Mutations Among Adults with Breast and Ovarian Cancer in the Caribbean’, were published 1 March in JAMA Network Open medical journal. It is the largest cross-sectional study of its kind.
They hope that the study’s findings will lead to better screening and treatment of Caribbean cancer patients, in their homelands and in South Florida. Breast cancer is the leading cause of death in Caribbean women, while ovarian cancer ranks fourth.
The mean age of patients with the BRCA mutations was younger, 40.7, compared to the 47.5 of patients without mutations, the research found.
Hurley and George, speaking to the Cayman Compass, said the research team found different mutations among each of the islands in the study.
“We found that it was different from island to island,” George said. “Each country had its own spectrum of mutations. Each country had its own unique genetic fingerprint.”
The team first came to Cayman in 2012 to carry out gene testing on 62 women who had either recovered from or were suffering from breast or ovarian cancer. A second round of expanded testing was done later, when advancing technology enabled more gene sequencing to be examined.
In Cayman, for the purposes of the study, Hurley and George tested women who had at least one Caymanian grandparent. “6.3% were found to have one of the breast cancer genes, which is within the range of the US or European numbers. It’s a lot lower than in other Caribbean countries,” George said.
The gene mutations found in Cayman were BRCA1 and BRCA2, the scientists said.
Hurley said that people found to have either of those mutations had, by the age of 70, a 65-80% chance of developing breast cancer, and up to a 40% chance of developing ovarian cancer.
She and George advise that anyone with a family history of breast or ovarian cancer should consider having the gene screening done, so they can take steps to mitigate their risk.
In total, the Sylvester researchers tested 1,018 adults with breast or ovarian cancer.
Initially, researchers screened only for the BRCA1, BRCA2, PALB2 and RAD51 mutations, but toward the end of the study, as multi-gene panel testing became cheaper and more available, study participants underwent a full next-generation sequencing on a panel of 30 genes.
In the Bahamas, the researchers’ work has already changed the guidelines for breast cancer screenings. The American Cancer Society recommends screenings start when women hit their 40s, but Bahamian women with a first-degree breast cancer relative now are advised to begin ultrasounds in their mid-20s.
Unlike in the UK, where women are invited to get a mammogram every three years starting at age 50, in Cayman, routine mammogram screenings are done every other year, starting at age 40, or as recommended by a doctor.
Dr. Sook Yin, medical director of the Cayman Islands Cancer Society, who liaised with the study authors on the Cayman part of the research, said back in 2012 when the testing was first being done, there had been reluctance among some Caymanian patients to take part.
This was due to two factors, she said – the perceived stigma of having cancer in the family, and concerns that if a test showed they had an inherited gene that made them predisposed to breast or ovarian cancer, they would be penalised by their health insurance companies.
“They were concerned they might face higher premiums or might be excluded from having insurance,” Yin said.
While genetic-sequencing tests are not currently done on island, they are readily available in the US and swab samples can be sent by mail by anyone who wants to take them. Yin said she had a number of patients who had done these types of genetic testing, and who found that they had inherited genes that made them susceptible to certain types of cancers.
“Now that genetic testing is so easily available, people can request it from their doctor and just send it off,” she said. As a result, she has had some patients, who have the BRCA genes and who have close relatives who have had breast cancer, that had opted to undergo double mastectomies because they knew their risk of developing cancer was so high.
Actress Angelina Jolie famously underwent a preventative double mastectomy in 2013 after a test showed she had the BRCA1 gene. Her mother had fought cancer for a decade and died at the age of 56. Jolie said her doctors estimated she had an 87% risk of developing breast cancer and a 50% risk of ovarian cancer.
Other factors involved
Hurley said that while the research had found that 25% of the cancer patients in the Bahamas study had the mutated genes, that meant that it was not yet known why the other 75% developed breast or ovarian cancer. “The women who had the mutation developed cancer at an average age of 33-35; for the other women, without the mutation, it was 48. That’s really young. There is way more to this story.
“Now that genetic sequencing is so cheap, it can be commercially available and viable in Caribbean islands. Once you know you have one of these genes, you can mitigate your risk, and that’s a very powerful thing – to be able to take control of their lives and do risk- mitigation strategies.”
Hurley said over 90% of the women tested in the Caribbean islands had found their own breast cancer through self-checks or because their doctor had found a lump, rather than through routine mammogram screening. The majority of the women in the study were also found to be in stage 3 or 4 by the time they were diagnosed, she said.
“Perhaps we have to work on a different way of having women being aware of their own breasts,” Hurley said. “Instead of finding a mass the size of grapefruit, which is what happens, maybe they’ll find it when it’s the size of a grape. Perhaps, instead of a monthly breast check, there’s a check you can do every day while putting on your bra – look in the mirror, check your breasts daily to see if there is any change from the day before – something that takes less than 10 seconds.”
Janette Fitzgerald, chief administration of the Breast Cancer Foundation, said the charity is seeing a lot more women under the age of 40 with breast cancer than it would expect.
To help with early diagnoses and timely treatments, she said, “All we can do is target women of all ages. We do go to the schools and talk to the 14-and-above age group. Our awareness programme stresses that all ages are vulnerable.”
Dr. Ginny Hobday, the Breast Cancer Foundation’s medical director, said the Hurley/George research had highlighted that that geography plays a part in cancer risk factors, and the findings from the study could be used to help identify high-risk groups and lead to earlier diagnoses and treatments, especially for younger women.
The precise prevalence of breast or ovarian cancer in Cayman is not known, as the only islandwide record of cases is kept on the Cancer Registry, but it is not compulsory for medical professionals to register each case.
“Because we don’t have a mandatory Cancer Registry, everything is anecdotal,” Hobday said. “It’s been a problem for a long, long time.”
According to the Cancer Society, most local insurance plans include at least $200 in their wellness benefits that can be used toward the cost of mammogram screening, and it urges women to take advantage of this.
Following the recent publication of their findings, Hurley and George are now looking into the ‘epigenetics factors’ of the study group. Hurley explained, “Inherited mutations, which are called germline mutations, are hundreds or even thousands of years old. But the epigenetic changes can be seen in days, weeks or months. This interaction between the DNA that you inherited from your parents and the epigenetic changes in your DNA that are caused by fertility factors, environmental exposures, your diet and lifestyle are fascinating.”
Breast cancer diagnosis age in Cayman
Total cases: 245
Source: Breast Cancer Foundation
Percentage of cancer patients with breast or ovarian cancer gene
Trinidad and Tobago: 12%
Source: Hurley and George gene-sequencing study