NEW ORLEANS—When talking with women about their personal risk of developing breast cancer, “terms such as relative risk are not very useful,” Patricia Kelly, PhD, said at the American Society of Breast Disease annual meeting, co-sponsored by the Ochsner Medical Foundation, New Orleans.
Women can be easily misled by statistics from clinical research trials, said Ms. Kelly, a specialist in breast cancer risk who serves as a medical geneticist at Catholic Healthcare, San Francisco. She called for investigators to translate their findings into a more meaningful format and for clinicians to communicate such information more effectively to patients.
Physicians should focus less on concepts such as “relative risk” or “percent increase or decrease in risk.” Instead, she said, they should speak in terms of the actual numbers of women who will be affected and the patient’s risks for the next year and for the next 5 years.
“Relative risk is a way to keep biostatisticians and epidemiologists from being criticized,” she said. “It is time to move beyond taking care of the epidemiologists and get the information we need for our patients. We need to demand from those who publish data that they give us information that is useful to us and to our patients. We should ask that the studies present the risk as risk over time.”
Risk of the BRCA2 Mutation
Women generally perceive their risk to be much higher than it actually is because of the manner in which such information is provided, she said.
As an example, she pointed to the risk of breast and ovarian cancer conveyed by a BRCA2 mutation. Among carriers aged 31 to 39, the lifetime risk of developing breast cancer is 11% and there is no increased risk of ovarian cancer; at ages 40 to 49, the risk is 16% for breast cancer and 0.4% for ovarian cancer; at ages 50 to 59, it is 20% and 7%, respectively; and at ages 60 to 69, it increases to 36% and 20%.
Several major breast cancer trials illustrate her point, she said. The Nurses Health Study, for example, found a 1.5-fold increased risk of breast cancer among women who took hormone replacement therapy. Such “increased risk” turned many women against the idea of hormone replacement therapy, although their actual risk of developing breast cancer is much lower than it sounds.
“The 1.5 increase in risk in this study actually meant that among 100 women who took hormones until age 60, there were 4.1 cases of breast cancer, compared with 3.8 cases among women not taking hormones. The difference was 0.3 cases. For women who took hormones to age 70, there were 6.9 cases per 100 vs 6.3 for those not on hormones,” she said. “Moreover, most studies have found no increase in the risk of breast cancer in women taking hormone replacement therapy.”
Tamoxifen Chemoprevention
She applied the same logic to the NSABP Tamoxifen(Drug information on tamoxifen) Prevention Trial, which found a significant 49% reduction in risk among healthy high-risk women taking tamoxifen (Nolvadex). “This number was impressive to most people,” she said, “but it’s the difference between 4.3 cases of invasive breast cancer vs 2.2 per 100 women over 5 years’ time.”
Patients need to have the risk put into perspective, she said. “For comparison, what is the risk of choking while eating?” she asked. “And they need to hear from us loud and strong what degree of risk is reasonable and how small a risk of 1% a year, for example, really is.”
In considering tamoxifen chemopre-vention, she said, “my patients respond very differently to hearing ‘49% reduction’ on the one hand and ‘2 women per 100 over 5 years’ on the other. We’re talking about very small numbers.”
Additionally, she said, recent data indicating a 20% increased breast cancer risk from oral contraceptives really translated into one case out of 3,700 women, and a 40% increase in risk imparted by two glasses of red wine daily amounts to one additional cancer per 1,500 women.
She advised physicians to read critically and to look at the spread of the confidence interval. “If it is very wide, it is telling you the numbers are too small on which to base a definitive (or even approximate) clinical decision.”
A 9-year breast cancer survivor and spokesperson for the Louisiana Breast Cancer Task Force praised Dr. Kelley’s efforts to encourage physicians at the meeting to communicate more effectively with women. “Rather than empowering women, we are frightening women to death with the statistics,” said Cathie McMichael, of Slidell, Louisiana.
Andrew Seidman, MD, of Memorial Sloan-Kettering Cancer Center, added, “There is an epidemic of fear. We physicians have a tremendous responsibility to make our patients understand the statistics and how they impact their own lives.”
Patients can be easily misled by statistics, Dr. Seidman said. “Women considering taking tamoxifen to reduce their risk for breast cancer need to know the absolute benefit in reducing their risk this year and over the next 5 years,” he commented.
