Zagouri et al. BMC Cancer 2010, 10:409 http://www.biomedcentral.com/1471-2407/10/409 Table 3 Expression of Hsp90 in invasive lobular carcinomas (ILC) and the normal adjacent ducts and lobules (mean ± SD) Adjacent normal ducts and lobules 2.16 ± 0.68 74.2 ± 11.2 7.00 ± 0.95 ILC 1.84 ± 0.63 59.1 ± 14.2 6.22 ± 1.01 Hsp90 intensity (score) Hsp90 positive cells (%) Hsp90 Allred score ap-value derived from Wilcoxon matched-pairs signed-ranks test been reported to positively associated with Hsp90 expression [7], it is tempting to speculate that downre- gulation of Hsp90 in ILC may be a c-erbB2 related event. However, no significant association was noted between c-erbB2 status and Hsp90 Allred score in our cohort; this null, inconclusive finding should be inter- preted with caution, as only seven cases were c-erbB2 positive. In other words, the small number of c-erbB2 positive cases may have blurred the association between c-erbB2 and Hsp90 at a certain extent. The present study comes to expand the results of our previous immunohistochemical study on LN lesions. In the case of LN we have postulated that the decreased Hsp90 expression may be partly due to the self-limiting, close-to-normal character of the lesion, as well as to the relatively milder stress response when compared to can- cer [14]. The present study uncovers an Hsp90 expres- sion pattern (relative decrease) which seems applicable to the whole continuum of lobular lesions and may be thus revealing of an inherent trend of the whole breast lobular series. Nevertheless, the fact that the finding seems to persist in the invasive lesions may suggest that the proliferation advantage in lobular lesions is an Hsp90-independent process. This hypothesis seems further supported by the fact that Ki-67 expression was not associated with Hsp90 expression in infiltrative lob- ular carcinomas. The downregulation of Hsp90 for the entire lobular series is a phenomenon which may be of particular clin- ical significance. Anti-Hsp90 drugs are currently tested in trials with very promising results [20-23]. Neverthe- less, no trials have focused on lobular lesions. Conse- quently, it would appear that the effects of Hsp90 Table 4 Detailed results of Allred score in invasive lobular carcinomas (ILC) and the normal adjacent ducts and lobules Allred score Adjacent normal ducts and lobules 4 5 6 7 8 Figures are frequency (percentage). 0 (0.0) 4 (12.5) 2 (6.2) 16 (50.0) 10 (31.3) ILC 1 (3.1) 6 (18.8) 14 (43.7) 7 (21.9) 4 (12.5) Page 5 of 6 pa 0.087 0.0001 0.007 targeting drugs should be evaluated separately on ductal and lobular carcinomas, since the effectiveness may be limited accordingly. In our cases, some epithelial cells of ILC showed scarce (i.e. <5%) nuclear Hsp90 localization; it should be noted that the aforementioned nuclear staining was not taken into account at the calculation of Allred score, as such a percentage may have been caused by technical reasons. Allred score was based exclusively on cytoplas- mic Hsp90 staining. Nevertheless, the significance of nuclear Hsp90 expression remains elusive, as some stu- dies have not documented any nuclear Hsp90 expres- sion in invasive ductal carcinomas [7], as opposed to other studies [24]. This finding has already been reported in invasive breast carcinomas and has been correlated with MHC class I expression [25]. In relation to the limitations of this study, it is worth referring to a number of points. Firstly, the small study sample should be declared; as a result, the present find- ings need to be reproduced in larger follow-up studies, so as to thoroughly examine the robustness as well as the clinical and prognostic implications of this immuno- histochemical study. Accordingly, the fact that the decrease in Hsp90 intensity was solely of borderline sta- tistical significance may not denote an inconsistency in results, as it could reach formal statistical significance in the context of a larger sample size (larger cohort). In any event, the Allred score, integrating both percentage and intensity, confirmed the decrease despite the rela- tively small sample size. Another limitation of this study pertains to the method performed (i.e. immunohistochemistry). Not- withstanding, Hsp90 downregulation might not be con- testable given its clear demonstration in a relatively less sensitive assessment (immunohistochemical procedure and visual scoring). To ensure the objectivity of the assessment, the percentage and intensity were assigned by two independent pathologists blind to one another’s results. Nevertheless, under the light of the above inher- ent limitations of the method adopted, the results need to be confirmed by other methods apart from immuno- histrochemistry (such as Western blot). Indeed, in vitro mechanistic studies seem indispensable for definitive conclusions; it should be acknowledged that such mechanistic studies were not feasible in the clinical