Correlation of metabolic activity and traditional prognostic factors of primary breast cancer

Objectives Correlations between SUVmax and different prognostic factors are well studied issues, but there are still unclear questions. The aim of this retrospective study was to examine the correlation between SUVmax and immunohistochemical characteristics of the tumors as well as clinical status of the patients to provide additional data for further analysis.

Methods We evaluated the initial FDG-PET/CT scans and histological reports of 136 breast cancer patients. To minimize bias caused by partial volume effect subjects with tumors smaller than 2 cm (5 patients) were excluded. Mann-Whitney U test and Spearman’s correlation were performed to find associations between SUVmax and the following clinicopathological prognostic factors: hormone and HER2 receptor status, Ki-67 proliferation index, the presence of local lymphatic and distant metastases.

Results We found associations between SUVmax of the primary tumor and the following parameters: hormone receptor status (p=0.001), HER2 receptor status (P=0.02), presence of regional (p=0.000) and distant (P= 0.029) metastases. SUVmax values were higher in hormone receptor negative, HER2 receptor positive cases, and in patients with local lymphatic or distant metastases. A positive relationship was found between SUVmax and Ki-67 proliferation index by Spearman’s correlation (r=0.493, p=0.000).

Conclusions Our results are mainly in concordance with other studies. Although, the literature is contradictory in the case of HER2 receptor status as many articles found no correlation between HER2 status and SUVmax, our findings confirmed the theory that higher SUVmax is associated with bad prognostic factors.