Our NAF and ductal lavage experience among women from BRCA mutation-positive families represents the largest analyzed series to date, with 874 person-years of observation. In the current study, we identified significant positive multivariate correlations between ductal lavage cell count adequacy and premenopausal status, having breast-fed, and the presence of NAF for all women combined. When evaluating mutation carriers separately, only having breast-fed and the presence of NAF were positively associated with cell count adequacy. Prior BSO was associated with significantly lower cell counts. We also identified univariate correlates of successfully obtaining NAF, which included older age (≥40 years), mutation-negative status, and absence of SERM exposure. In multivariate analysis, being postmenopausal, when compared with being premenopausal, was the only significant predictor of success obtaining NAF. Being postmenopausal and having prior salpingo-oophorectomy lowered the odds of having NAF when compared with postmenopausal women with intact ovaries (OR, 1.3 versus 4.8).
Compared with previous reports of ductal lavage in women with known BRCA1
mutations, our findings differ in several important aspects. First, ours is the largest series of ductal lavage results in mutation-positive women, which should produce more stable estimates regarding associations of interest. Overall, the women in our study were ~3 years younger (40 versus 43 in two prior studies; refs. 13
) than previous reports. They were less likely to have had breast and/or ovarian cancer (14% versus 40% and 35%; refs. 13
) and more likely to be nulliparous (41% versus 15% and 29%; refs. 13
). Our postmenopausal subjects were somewhat more likely to have undergone prior BSO (87% versus 84% and 70%; refs. 13
). The number of women who yielded NAF shows the variability in the growing NAF experience (26% versus 13%, 52%, and 60%) as part of the ductal lavage procedure (8
) in women with known BRCA1
Our univariate analysis confirmed earlier findings that NAF expression correlates positively with cellular yield on ductal lavage (13
) and further identified a prior history of breast-feeding, having at least one live birth, and no current use of a SERM as positively associated with obtaining an adequate ductal lavage cell count.
Of note, SERMs were used only by mutation carriers in our series (13 of 146); none of the noncarriers (0 of 23) were current or past SERM users. Only one mutation-negative woman was currently using MHT; all remaining 17 MHT users were carriers. Women not using either a SERM or MHT were more likely (OR, 7.09; P = 0.07 and OR, 3.14; P = 0.07, respectively) to have an adequate cell yield, although these findings were of borderline significance. This finding in relation to SERM use is consistent with the known antiestrogenic effect of SERMs on breast ductal epithelial proliferation. Women taking MHT in this group represented women who had undergone risk-reducing salpingo-oophorectomy to lower the risk of ovarian cancer. This suggests that the loss of estrogen’s proliferative effect on the breast is not reversed by the post-risk-reducing salpingo-oophorectomy administration of MHT.
Like other groups, we did detect cytologic atypia in ductal lavage fluid from both NAF-yielding and non-NAF-yielding ducts; however, our atypia rates were much lower (3% versus 28% and 21%) than those previously reported in mutation carriers (13
). Interobserver variability in cytology scoring can affect the reported prevalence of ductal lavage atypia. To reduce the interobserver variability in our series, all specimens were reviewed independently by two cytopathologists (A.D.A. and A.C.F.), who were both trained and mentored in evaluating ductal lavage specimens. Cytologic atypia in ductal lavage samples was not associated with any significant physical examination, mammography, or MRI abnormalities in any of our patients either at the time of ductal lavage or during up to 4 years of prospective follow-up. This experience is different from that of a prior report, which identified MRI “abnormalities” in six of seven breasts with ductal lavage-related cytologic atypia (34
). Three of those seven women were BRCA
mutation carriers, none of whom had documented neoplasia on follow-up of their imaging findings (34
With respect to ductal lavage sample adequacy, despite obtaining 145 specimens for cytologic review (145 of 306 ducts attempted), only 92 specimens contained sufficient numbers of exfoliated breast epithelial cells to be considered adequate (31%) for cytologic review. This finding is similar to a recently reported 31% rate of adequate cell counts for cytologic review obtained by ductal lavage in 86 women at “high risk” of breast cancer when compared with 100% adequate cell counts obtained by random periareolar fine-needle aspiration (5
). Several other groups have reported their experience with reduced NAF retrieval rates (8
), low ductal lavage cell yields (6
), and low reproducibility of cytologic findings and participants’ return rates (6
) and have concluded that, among women at high risk of breast cancer, ductal lavage is of limited clinical value for repeated sampling of the breast epithelium.
Other groups have reported higher rates of adequate cell counts in BRCA1
mutation carriers (87% and 61% in 56 and 52 mutation carriers, respectively; refs. 13
). The differences in the characteristics of the group of women in the current study related to age, parity, and prior personal history of breast and ovarian cancer may explain these differences. The patients’ extended 2-day visit may have had an unexpected detrimental affect on the NAF and ductal lavage procedures. NAF and ductal lavage were attempted only once per annual clinical visit and were the last procedures of a 2-day breast and ovarian cancer screening visit. It is possible that, if time had permitted multiple attempts at NAF, our NAF and ductal lavage cellularity rates could have increased. It is also possible that patient fatigue or mild dehydration may have lowered the overall success rate. It is also possible that our sample size, which is nearly four times that of prior reports, has permitted us to make estimates of various NAF and ductal lavage parameters that are more precise and stable than those derived from smaller studies.
Strengths of our analysis include the size and geographical diversity (36 of the 50 states, one U.S. Territory, Bermuda, and Canada) of the study population, the large proportion of subjects who are BRCA mutation-positive, and its prospective design. In addition, the majority of study participants were unrelated to one another, unlike the more common scenario in tertiary care high-risk clinics, in which multiple members of the same family are more likely to be seen. Our study subjects represented 127 separate, unrelated families. Finally, a unique feature of this study was the deliberate enrollment of several mutation-negative women, which was intended to serve as a comparison group.
Based on the very high lifetime risk of developing breast cancer, BRCA1/2
mutation carriers would seem to be ideal candidates for ductal lavage. However, in our experience, 74% (126 of 171) of potential candidates did not yield NAF, 37% (64 of 171) could not have a duct cannulated, and 59% (101 of 171) did not yield a cytologically evaluable sample. Thus, we were able to acquire a cytologically evaluable sample in only 41% of all subjects considered for ductal lavage. Our experience suggests that ductal lavage is not likely to play a central clinical role in breast cancer screening among high-risk women, because women find it painful and are reluctant to undergo multiple ductal lavage examinations over time (11
) and because the procedure fails to yield large enough numbers of exfoliated epithelial cells to permit reliable cytologic diagnosis or to support cell-based translational research activities. Systematic evaluation of alternative tissue acquisition strategies in large numbers of carefully studied BRCA
mutation carriers remains a high priority research focus.