'Knowledge Is Power': Knowing BRCA1/2 Status Tied to Survival

Veronica Hackethal, MD

July 21, 2020

A study has shown for the first time that knowing BRCA1/2 mutation status before a breast cancer diagnosis was associated with better survival.

The study, conducted among Ashkenazi Jewish women in Israel, showed that among women who knew their carrier status before they developed breast cancer, diagnoses were made at an earlier disease stage and 5-year survival was improved compared to women who learned their carrier status only after their disease had been diagnosed.

The study was published online on July 9 in JAMA Oncology.

"I don't want to belittle the complexities of knowing that you're a carrier. But I think these results really show that knowledge is power," first author Ephrat Levy-Lahad, MD, director of the medical genetics unit at Shaare Zedek Medical Center in Jerusalem, Israel, told Medscape Medical News.

Carrying a BRCA1/2 pathogenic mutation is associated with a 70% to 80% lifetime risk for breast cancer and about a 10% to 50% lifetime risk for ovarian cancer, depending on the specific mutation. Only about 10% of carriers will not develop either cancer during their lifetime.

The study provides support for genetic screening for pathogenic BRCA1/2 mutations, especially in high-risk populations, according to Levy-Lahad.

"For me, the results are part of a bigger picture.... I think we should be moving towards general population screening, certainly in high-risk populations like Ashkenazi Jews," she said.

In Israel, that decision has already been made: a new policy, introduced in January 2020, offers testing for common BRCA1/2 mutations for all Ashkenazi Jewish women.

However, women in other countries may also benefit from testing, she argues. About half of BRCA1/2 carriers in a general population like that of the United States do not have a family history that would indicate a need for testing. That means many women who carry these mutations may not be taking advantage of recommended surveillance and prevention measures, she said.

But screening for BRCA1/2 mutations becomes more complicated when applied to more general populations, she acknowledged.

About 2.5% of women of Ashkenazi Jewish descent carry pathogenic mutations for BRCA1/2, compared to 0.5% in the general White population.

Also, screening in the Ashkenazi Jewish population is probably simpler than in the general population. Just three mutations are definitely known to cause disease and need to be tested for among Ashkenazi Jews. Screening in a larger population would require full sequencing of the gene. That increases the likelihood of finding variants of unknown significance (VUSs), which muddies the water. Knowledge is incomplete about whether some of these VUSs increase cancer risk, and physicians do not always know how to manage them in women who test positive.

Moreover, Israel has a national health system. Screening in a country without universal health insurance such as the United States raises questions about whether follow-up would be covered by insurance carriers for women who test positive.

Mehmet Copur, MD, an oncologist at Morrison Cancer Center in Hastings, Nebraska, questions how general population screening could be done in "real life."

"These findings should be taken into consideration in the context of the patient population who would agree to genetic testing, who would agree to comply with the recommended guidelines for risk reduction, and who would have insurance coverage or resources to comply with the recommendations," Copur told Medscape Medical News.

"If BRCA-positive patients did not or could not follow these recommendations, the results would different," he added.

The most crucial component of screening for these mutations is genetic counselors, who are in short supply in the United States, according to Copur.

Another issue is that of cost. Genetic counseling is not always covered by insurance, especially for individuals who do not have a family history of BRCA-related cancers. Genetic testing is not cheap, and the costs of monitoring women who test positive could be prohibitive, especially in a healthcare system burdened by COVID-19.

"Whether our current healthcare system could bear the cost of such a change is up for debate. The screening itself may be feasible, but offering lifelong surveillance to every woman identified with mutations could present huge capacity issues," Copur said. "Maybe in the future, the healthcare system can be ready for such an undertaking, but I don't think we are there yet."

Although she acknowledges the differences in risk between Ashkenazi Jews and the general population, Levy-Lahad thinks not having screening is like "throwing the baby out with the bath water."

"Maybe we're not ready for total general population screening, but I think we have to start thinking along those lines," she said. "We have this incredible tool for cancer prevention, and we should really be using it, certainly in populations like Ashkenazi Jews."

Study Details

Researchers conducted a retrospective analysis that included 105 women diagnosed with breast cancer at Shaare Zedek Medical Center in Jerusalem between 2005 and 2016. Forty-two women knew they were carriers before their breast cancer diagnosis, and 63 learned of their carrier status only after diagnosis. Of the participants, 83% were Ashkenazi Jews. For both prediagnosis and postdiagnosis groups, the age at diagnosis was the same (50.4 years). For both groups, distributions of pathogenic mutations were similar. There were no significant differences in hormone receptor or ERBB2 status.

Among women who knew they were carriers before diagnosis, 80.9% (34/42) were diagnosed either with ductal carcinoma in situ or stage 1 disease. Only 9.5% (4/42) of these women were diagnosed with disease of stage 2 or higher.

In comparison, among women who learned their carrier status after diagnosis, 30% (19/63) had early-stage disease at diagnosis, and 52.4% (33/63) were diagnosed at stage 2 or higher (P < .001).

Compared to women who knew their carrier status before diagnosis, women who found out after diagnosis had 12 times higher odds of being diagnosed with disease of advanced clinical stage (P = .001) and eight times higher odds of being diagnosed with disease of advanced pathologic stage (P = .002).

A sentinel node biopsy was sufficient in 85.7% (36/42) of women who knew their carrier status before diagnosis; 7.2% (3/42) of these women needed a full lymph node dissection. In contrast, 3.2% (2/63) of women who learned their carrier status after diagnosis underwent sentinel node biopsy, and 34.9% (25/105) needed a full lymph node dissection (P < .001).

Among women who knew their carrier status before diagnosis, 54.8% (23/42) did not need chemotherapy at all, and none needed neoadjuvant chemotherapy. Only 4.8% (3/63) of women who learned their mutation status after diagnosis were able to forgo chemotherapy (P < .001); 22.2% (14/63) needed neoadjuvant therapy (P = .001).

These findings appeared to translate into better outcomes. Overall 5-year survival was significantly higher among women who knew their carrier status before diagnosis compared to women who found out afterward (94% [SE 4%] vs 78% [SE 5%]; P = .03). Only two of 42 women (4.8%) in the prediagnosis group died, compared to 16 of 63 (25.4%) in the postdiagnosis group.

Analyses that controlled for year at diagnosis showed that women who learned their carrier status before diagnosis had significantly lower risk for overall mortality compared with those who found out after diagnosis (hazard ratio [HR], 0.20; 95% CI, 0.04 – 0.93; P = .04). However, these results lost significance when controlled for age, socioeconomic index, family history, and gene variant (HR, 0.16; 95% CI, 0.02 – 1.4; P = .10).

Higher socioeconomic status (HR, 0.76; 95% CI, 0.6 – 0.97; P = .03), gene variant (BRCA2 vs BRCA1: HR, 0.15; 95% CI, 0.03 – 0.75; P = .02), and age at diagnosis (HR, 1.047; 95% CI, 1.003 – 1.093; P = .04) were all associated with overall mortality.

"I can't infer causation, but we suspect that the reason for these results is the difference in follow-up," Levy-Lahad said.

Most of the women (95.2%, 40/42) who knew their carrier status before diagnosis received their follow-up at the medical center's high-risk carrier clinic. Twenty-seven of 42 (64.3%) of these women were diagnosed with breast MRI. By contrast, only 1.6% (1/63) of women who found out their carrier status after diagnosis were diagnosed with breast MRI. Breast MRI is not routinely used for breast cancer screening but can be more sensitive than mammography for detecting breast cancer.

The study was funded by the Breast Cancer Research Foundation and by a gift from Ellie and David Werber to ShaareZedek Medical Center.

Levy-Lahad received grants from the Breast Cancer Research Foundation and from the Israel Cancer Association during the conduct of the study and personal fees from AstraZeneca outside the submitted work. Copur has disclosed no relevant financial relationships.

JAMA Oncol. Published online July 9, 2020. Abstract

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