Prospective trials comparing clinical outcomes of occasionally screened low-risk women with outcomes of low-risk women screened annually may overlook or misidentify breast cancers that exist but haven’t advanced. A better approach would be first conducting retrospective studies in which all women undergo newer methods of genetic testing, quantitative measurement of breast density, and complete documentation of conventional risk factors.
That’s the opinion of Stephen Feig, MD, of UC-Irvine, as stated ahead of print in the American Journal of Roentgenology under a provocative headline: “Personalized Screening for Breast Cancer: A Wolf in Sheep’s Clothing?”
Building a case for his conclusion above, Feig reviews the gist of various proposals, guidelines and recommendations as drawn from clinical trials conducted amid the hotly contested territory of breast-screening advice for women.
Taking up the question of whether proposals for personalized—i.e., restricted—screening make sense, he states that clinicians may tend to favor this approach for women “at supposedly lower risk” because the clinicians know that personalized treatments targeting individual tumors’ molecular makeup tend to work best.
“However, there are many reasons why this personalized approach may not be applicable to triage asymptomatic women for reduced screening or no screening,” he writes.
To support this stand, Feig points out that:
- There is no way to predict molecular characteristics of undetected tumors on the basis of a woman’s risk factors;
- There is no known relationship of breast cancer growth rates to risk status among women in the same age group; and
- There is no evidence that breast cancer growth rates vary according to family history, prior breast biopsy, or breast density.
“The main reason to screen low- and average-risk women less frequently would seem to be financial rather than medical,” he writes. “It is ironic that many personalized screening protocols advocate less frequent screenings of women 50 years old and younger, because it has been well established that breast cancers grow faster among women 40 to 49 years old.”
Limiting screening to only high-risk women would miss 75 percent of breast cancers, he writes, as the vast majority of women with breast cancer are not at elevated risk. Meanwhile, since breast density does not have "sufficient discriminatory power," denying annual screenings to women with nondense breasts would make them more susceptible to late detection.
“For most women, personalized screening is a euphemism for an unwarranted restriction of preventive health care,” writes Feig.
Unless and until each and every woman in the U.S. is screened according to the present guidelines of the American Cancer Society, the American College of Radiology and the Society of Breast Imaging—and with a sufficiently long follow-up at that—“subgroups for less frequent screening cannot be safely identified,” Feig maintains.
“Until that is successfully completed, personalized screening recommendations could remain a wolf in sheep’s clothing.”