Editor’s Note
	Scary, scary stuff

Craig Allred is one of the nicest people in our field, and it is ironic that every time I chat with him, I feel awful. My instantaneous bad humor has nothing to do with Craig personally, but rather the human implications of his work. Most specifically, it is his continued demonstration that many women with breast cancer are being denied an effective, relatively nontoxic intervention because of poor quality control in the performance and interpretation of estrogen- and progesteronereceptor assays.

Almost every medical oncologist and breast surgeon has heard about Craig’s presentation at the 2002 San Antonio Breast Cancer Symposium, which demonstrated that women with ER-negative DCIS do not benefit from tamoxifen. Far fewer physicians, though, are aware that many women’s tumors that are determined to be ER-negative by community-based laboratories would be considered ER-positive in Craig’s laboratory. A ton of time, money and effort has gone into the development of the first truly targeted therapy for breast cancer, and it is pitiful that many women will not reap the potentially substantial benefits of this treatment because we can’t get their ER status right.

This compelling issue has been on the table for a decade without much reaction. Craig, in his gentle manner, finds this “a little disheartening.” A little disheartening? If I’m a person whose disease has relapsed without having been given the option of receiving adjuvant endocrine therapy based on a false-negative result, I’m profoundly disheartened. In fact, I’m angry as hell.

While the “powers that be” muddle over resolving this mess, it is imperative that individual physicians and patients approach tumors labeled as “ER-negative” with considerable skepticism. Sure, some breast cancers do not express ER, but many more may have lower-level positive values that correlate with benefit from endocrine therapy. Consequently, oncologists must consider a second pathology opinion for any woman whose tumor is labeled as ER-negative. As discussed by Craig on this program, perhaps one out of four of these tumors might be reclassified as ER-positive.

The same issues might be said about quality control in HER2 testing, although the implications are perhaps less in the adjuvant setting. That said, in a recent case-based CME conference I moderated, an oncologist presented the case of an 87-year-old woman with bone and lung metastases and a previous HER2 assay result that scored zero on immunohistochemistry (IHC). The treating physician was suspicious of the rapid progression of this woman’s cancer and had the original tumor retested by fluorescence in situ hybridization (FISH). This proved to be positive for HER2 amplification and, fortunately, the woman did well for some years on trastuzumab-based therapy.

Patients should not need to rely on astute physicians to be rescued from outdated pathology or pathologists. We must demand better quality from our laboratory colleagues.

— Neil Love, MD
NLove@ResearchToPractice.net

Related comments from this program

False negatives in ER analysis

In my practice, I consult on several hundred difficult cases each year. Many of these are sent for repeat ER testing and the conversion rate from negative to positive is 20 to 30 percent. The reasons for false negatives have been studied in detail in invasive cancer and the same errors probably occur when assessing the ER status in patients with DCIS.

The single biggest contributor is the antigen retrieval, which is an artsy part of the assay in which we try to reverse the cross-linking between the proteins caused by the initial formalin fixation. Another major problem is the antibody selected. Dozens of antibodies are available and they are not equivalent in sensitivity and specificity.

Another significant error is setting the cut point for positivity too high. It is usually set arbitrarily rather than based on clinical studies, and averages 10 or even 20 percent across the country. In invasive disease the cut point is much lower; almost so low that if it’s measurable, there’s probably a good chance the tumor will respond to hormonal therapy. The cut point we use — one percent — is based on clinical trials involving invasive breast cancer, but when applied to the B-24 DCIS study, the results were reasonable.

It’s worrisome that many community labs simply report the ER status as positive or negative. A comprehensive report provides an impression as to positivity or negativity of the specimen, a percent or proportion of positive cells, and may footnote relevant clinical trials.

— D Craig Allred, MD

Quality control of ER assays

Quality assurance is an important issue in ER testing — the stain needs to be nuclear, the pathologist’s experience is important, and we’ve learned that even a small amount of ER staining confers clinical sensitivity to hormone therapy. Even if only five percent of the cells stain, the entire tumor mass may respond to hormonal therapy and this may be due to a cell cycle-specific phenomena or the biology may be such that we achieve a cytostatic effect, or even an apoptotic effect, when only a fraction of the cells express ER.

We need to reassess how we define ER status. Some proponents of a revised scaling contend that even five percent of tumor cells with 1+ staining would qualify as ER-positive. A qualitative reading alone is no longer acceptable; more labs are reporting intensity and some provide a histoscore, which is a composite based on the percentage of positively staining cells and the intensity of staining. Hormonal therapy has the single greatest impact on outcome, so it’s important that tumors are classified accurately.

— Debu Tripathy, MD

Accuracy in HER2 testing

In HER2 testing, we see false positives and false negatives. One reason for this is that tissue preservation can destroy protein epitope and with the standard antibody assay, we may not obtain an accurate representation. In false negatives, the protein is present, but the fixation technique can make the protein less immunoreactive. In false positives, for whatever reason, the antibody assay stains nonspecifically.

In certain cases, DNA testing with FISH is important because DNA is more stable than protein. Experience has taught us that a very high level of protein staining, meaning 3+ with the standard IHC, truly represents a lot of protein; however at the 2+ level, approximately 25 to 50 percent will be positive by gene testing, which is why it’s important to verify a 2+ with FISH. The zeros and ones are rarely positive by FISH, and remain controversial. Some clinicians also perform FISH in cases with aggressive features of either the markers or the clinical history.

I believe it’s appropriate to perform HER2 testing on every primary breast cancer tumor specimen because the information may become important at some point in the future. Data from the cooperative groups show that 10 to 20 percent of the time, IHC scores are reclassified when central lab testing is compared to community labs. The NCCTG published a small pilot study showing the same discordance rate with FISH. It appears that the throughput of the lab is the single most predictive factor in accuracy, and labs that perform more than 300 or 400 tests per year have better accuracy rates.

— Debu Tripathy, MD

Allred D et al. Estrogen receptor expression as a predictive marker of the effectiveness of tamoxifen in the treatment of DCIS: Findings from NSABP Protocol B-24. Breast Cancer Res Treat 2002;81(Suppl 1);Abstract 30.

Harvey JM et al. Estrogen receptor status by immunohistochemistry is superior to the ligandbinding assay for predicting response to adjuvant endocrine therapy in breast cancer. J Clin Oncol 1999;17(5):1474-81. Abstract

Paik S et al. Real-world performance of HER2 testing — National Surgical Adjuvant Breast and Bowel Project experience. J Natl Cancer Inst 2002;94(11):852-4. Abstract

Roche PC et al. Concordance between local and central laboratory HER2 testing in the breast intergroup trial N9831. J Natl Cancer Inst 2002;94(11):855-7. Abstract

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