Prognostic significance of total choline on in-vivo proton MR spectroscopy for 10-year survival in patients with: hormone receptor-positive, HER2-negative early breast cancer

Abstract

Purpose In-vivo proton magnetic resonance spectroscopy (MRS) is a non-invasive method of analyzing choline metabolism that has been used to predict breast cancer prognosis. A strong choline peak may be a surrogate for aggressive tumor biology but its clinical relevance is unclear. The present study assessed whether total choline(tCho), as measured by proton MRS, can predict survival in patients with hormone receptor(HR)-positive, HER2-negative early breast cancer. Methods The study cohort included 560 breast cancer patients who underwent diagnostic single-voxel proton MRS (3.0T scanner) prior to first-line surgery from March 2011 to July 2014. The relationships between tCho compound peak integral (tChoi) values and biologic subtypes were analyzed, as were the effects of tChoi on 10-year disease-free survival (DFS) and overall survival (OS). The clinical significance of tChoi was also analyzed using Harrell's C-index. Results Of the 560 patients included in this study, 261 had HR+/HER2- breast cancer. Mean tChoi differed among patients with HR+/HER2- (15.5), triple negative (20.6), HR+/HER2+ (17.1), and HR-/HER2+ (15.0) breast cancer (p = 0.07). 10-year DFS differed significantly between HR+/HER2- with tChoi < 15 and ≥ 15 (p = 0.017), with differences differing significantly for late (5–10 years; p = 0.02) but not early (0–5 years; p = 0.323) recurrence. Cox regression analysis showed that tChoi was significantly predictive of 10-year DFS (p = 0.046, OR 2.69) and tended to be predictive of late recurrence (HR 4.36, p = 0.066). Harrell’s C-index showed that the Ki-67 index (AUC = 0.597) and lymphovascular invasion (AUC = 0.545) were also predictive of survival, with the addition of normalized tChoi improving the AUC to 0.622 (p = 0.014), indicating better predictive power. Conclusion A tChoi determined by in vivo MRS was predictive of prognosis in patients with HR+/HER2- early breast cancer. This parameter may serve as a valuable, non-invasive tool to predict prognosis when combined with other known prognostic factors.