That HER2 is prognostic of outcome in breast cancer is
unquestioned. As Jeffrey Ross at Albany Medical College put it: “Today, no one
I know doubts in any way that, in the absence of anti-HER2 therapy, HER2+
breast cancer is an unfavorable subtype and HER2+ status by IHC or FISH is a
significant and independent prognostic factor.”
Ross helped shape HER2’s reputation as a particularly
aggressive form of breast cancer. In 1998, Ross and co-author Jonathan Fletcher
published a review of
47 studies of HER2. Each study was checked for an “impact” on prognosis, either
univariate or multivariate. (Appendix C lists the 47 studies.)
Univariate findings can be misleading, often losing
significance when multiple factors are taken into account. Regarding the more
robust multivariate analyses, Ross and Fletcher reported that 28 (60%) of 47
studies found multivariate impact. The remaining 40% of studies either found no
multivariate impact or didn’t conduct a multivariate analysis.
Counted by cases, 10,142 (67%) patients out of 15,248 were
in studies found by Ross and Fletcher to have a multivariate impact. Their
review concludes: “The preponderance of evidence indicates that HER- 2/neu gene amplification and protein
overexpression are associated with an adverse outcome in breast cancer.”
However, the review’s conclusion depends on miscategorizing
9 of the 47 papers examined. Correctly categorizing these 9 studies to reflect
their actual findings overturns the conclusion that HER2 is prognostic. The preponderance of evidence is inverted and points to no adverse outcome from HER2 (Table 1). Similarly, the number of cases supporting a prognostic value for HER2 fall from two thirds to less than half (Table 2).
Table 1: Number of studies finding HER2 independently prognostic in
Table 2: Number of cases in studies finding HER2 independently prognostic
in multivariate analysis
Appendix A lists the 9 studies and justification for each
Ross did not dispute the recodings. Provided with the
information in Appendix A and asked if he agreed with the recoding, Ross replied:
“I am traveling in Europe and have limited time to review. It is certainly
possible that the studies you have cited were not perfectly listed in my
manuscript from so many years ago.”
Ross and Fletcher’s review suffers from multiple shortcomings.
(Appendix B enumerates important but secondary flaws.) However, the miscoding
of papers in Ross and Fletcher’s review is sufficient to overturn the paper’s
Conflicts of interest
Investigations of HER2 as a prognostic factor produced contradictory
findings and argument—resolved by Ross and Fletcher. Of note, commercial
interests played a role in several of the studies they reviewed and the review
Among the 47 papers examined, four [4, 10, 29, 48] list at
least one author with a corporate rather than academic affiliation. One
abstract  includes an author who was then
a director of diagnostics at Oncor, maker of a HER2 test. All five studies reported
HER2 as prognostic.
In their review, Ross and Fletcher report being consultants
for Oncor. However, according
to Bloomberg, Ross was Medical Director at Oncor beginning in late 1995 and later
Chief Medical Officer when his review with Fletcher was published in 1998. Ross
confirmed the accuracy of Bloomberg’s information. The FDA rejected
Oncor’s test in 1995 but, as reported
in the New York Times, Oncor won
approval in 1998.
It is likely true, as Ross stated, that today no one
questions that HER2 is prognostic in breast cancer. However, this supreme
confidence needs to be recalibrated.
Appendix A: Recoded papers
Of the 47 studies, the nine below were recoded:
 (Battifora et al.): Yes to No
The paper reports: "Stepwise Cox Regression: This analysis
identified independent prognostic factors of DFS and OS when all variables were
considered together. Independent predictors of DFS included stage of disease,
histology, and nuclear grade. Nuclear grade and stage were the only significant
predictors of OS."
 (Lovekin et al.): Yes to No
The paper reports: “Multivariate analysis (Cox,
1972) was used to identify whether c-erbB-2 was of independent prognostic
significance. In the context of the temporal variables, tumour size and lymph
node stage, cell membrane staining was found to have independent significance
as a prognostic factor but significance was lost when histological grade was
included in the analysis."
 (Dykins et al.): Yes to NA
No multivariate analysis
 (Paterson et al.): Yes to No
The paper does not state HER2 is independently prognostic in
a multivariate analysis or provide the statistics relevant to such a statement.
The authors do suggest possible confounding of prognostic factors: “our study
design precluded direct determination of the interrelationships of c-erbB-2 [HER2]
amplification with conventional disease parameters.”
 (Molina et al.): Yes to NA
No multivariate analysis
 (Press et al.): Yes to NA
No multivariate analysis
 (Descotes et al.): Yes to NA
As its title states, the paper is a “correlation study between
Her-2/neu amplification and prognostic factors.” No disease outcome data are
included in the paper.
 (Têtu et al.): Yes to No
The paper reports that HER2 was predictive of treatment
resistance, not prognostic: “The difference in survival
rates between cases was only significant among patients submitted to adjuvant
chemotherapy or hormone therapy."
 (Charpin et al.): Yes to NA
No multivariate analysis
Appendix B: Additional methodology issues
How the 47 papers reviewed by Ross and Fletcher were
selected is not described. In email, Ross wrote that “if you just limit the
publications cited to those finding HER2 positive rates between 10 and 30% the
prognostic impact of HER2+ status in the pre-anti-HER2 targeted therapy era was
However the review includes Dittadi et al.  which
describes a “high risk” group comprising 44% of all cases, well above 30%. Ross
and Fletcher count the study as supporting the independent, multivariate
prognostic impact of HER2.
Berger et al.  and Descotes et al.  only examine
correlations between biomarkers not with disease outcomes and should not have
Ross and Fletcher included two studies [42, 49] for which
there are only abstracts. More generally, the studies included were not graded
An unknown number of papers were omitted, potentially
introducing a selection bias. An omitted paper from Zhou et al. (1989), for
example, found no prognostic value for HER2. On the other hand, Wright et
al. (1989) also was not included but
found HER2 independently prognostic. Other possible biases in the literature,
against publishing, for example, are not examined.
Reviews frequently require a minimum number of cases for a
study to be included. Indeed, a number of the papers reviewed by Ross and
Fletcher attribute the conflicting results in HER2 studies in part to studies
with small numbers of cases.
One study  had 37 cases. Ross and Fletcher record it as
finding HER2 prognostic in univariate analysis but the paper contains no p
values, perhaps because n is so small. O’Malley et al.  does not state the
number of HER2 positive cases that provided the basis for the conclusion that HER2
was prognostic in multivariate regressions. (The corresponding author did not
reply to an email inquiry.)
A 2002 review of
prognostic factors in node-negative breast cancer specified inclusion criteria
and set a minimum number of cases (200). The paper concluded HER2 is not
No quantification of prognostic influence
Ross and Fletcher do not provide summary statistics based on
a pooling of results. Heterogeneity of the study designs perhaps made this
difficult or impossible. However, if heterogeneity prevented statistical summarization,
that would be an important finding to report.
The review includes a table of 18 prognostic factors in
breast cancer but makes no comparison of their relative strength and clinical
value. The prognostic value of HER2 varied widely. In , the p value rested at
precisely 0.05. Nodal status and tumor size were vastly more prognostic: p <
0.0001 and p = 0.003 respectively. Quénel et al.  found HER2 weakly
prognostic: "in our hands, c-erbB2 [HER2] had a poor prognostic value in
comparison with the classical prognostic variables…” However, whether such weak
prognostic value is general among the papers finding HER2 prognostic is not
examined by Ross and Fletcher.
Differences in treatment of cases occur within and between
studies but the paper does not control for confounding of prognosis with
predicting resistance to treatment.
HER2 positive undefined
Different studies used different definitions of HER2
positive. Even today, the definition of HER2 positive and the search for the
best HER2 assay continue to be active areas of study. Ross and Fletcher
identify the different assays used in HER2 determination (e.g. IHC, FISH) but
cut points are not extracted.
Three studies [4, 20, 30] found amplification of HER2
prognostic. But each used a different cut off for gene copy number: six, three,
and seven respectively. A single threshold would likely change the findings of
these studies and affect the count of studies finding HER2 prognostic.
Some papers determined cutoffs and comparison groups based
on achieving statistical significance. One study  found HER2 prognostic by
creating a “high risk” group that combined cases with the lowest and the highest expression of p185. The
low expression group had the worst
outcome. Dittadi et al. go on to conclude p185 was independently prognostic in
a multivariate analysis. Slamon et al.  simply dropped 23 cases with 2-5
copies of HER2. This remarkably unscientific omission enabled comparing a group
with one copy of HER2 to those with six or more, providing the basis for the
claim HER2 was independently prognostic in a multivariate analysis.
Negative findings not counted, contradictory findings are
Studies with even a single positive finding were counted by Ross
and Fletcher as evidence supporting HER2 as a prognostic factor. The number of negative findings is not reported. For example, O’Reilly et
al.  found HER2 prognostic for relapse-free survival but not overall survival in node-positive
disease. Ross and Fletcher count  as one of 28 papers supporting the finding
that HER2 is prognostic.
Quénel et al. , conducted multivariate
analyses for three clinical outcomes for three groups. Among the nine tests in total, HER2
showed prognostic value in two and no prognostic value in seven. Ross and
Fletcher count  among the papers showing that HER2 is prognostic.
Ross and Fletcher’s design also allows studies with opposing
findings to be counted as finding HER2 prognostic. For example Gusterson et al.  found HER2 prognostic in node-positive
but not node-negatives patients. However, Giai et al.  found the opposite.
The papers contradict each other but both are counted as showing HER2 is
prognostic by Ross and Fletcher.
Appendix C: Citations for the 47 studies reviewed by Ross and Fletcher
Footnote numbers are those used by Ross and Fletcher. The
same numbers are used throughout this article.
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