Contralateral Synchronous Breast Cancers Are Less Suspicious on Imaging

The objective of a recent study was to compare imaging, clinical, and pathological features of primary cancers and that of contralateral synchronous breast cancers (SBCs) in Asian women and to assess the effectiveness of detecting these cancers on mammography and ultrasound (US).

The study has concluded that bilateral whole-breast US has a role in detecting bilateral synchronous breast cancer.

This was a retrospective review of 62 bilateral SBCs in 31 patients from a single academic institution.

Results of the Study
The average patient age was 49 years. Most patients initially presented with clinically palpable masses, and 24% presented with bilateral palpable masses. The mean tumor size of all invasive cancers was 2.2 cm, and most contralateral cancers were significantly smaller. Approximately 50% of contralateral SBCs were ductal carcinoma in-situ. Most index cancers were invasive ductal carcinoma.

The sensitivity of mammography in detecting the index cancers was 87% and the sensitivity of US was 97%. The sensitivity of mammography in detecting contralateral SBCs was 55% and that of US was 90%. However, 42% of the contralateral SBCs were detected only by US.

Overall, mammographic morphologies of the index cancers were significantly more suspicious, and most index cancers were categorized as either BI-RADS categories 4C or 5. Almost all patients had either heterogeneously dense or extremely dense parenchymal patterns on mammograms.

Conclusions
Compared with mammography, bilateral whole-breast US has a higher sensitivity in detecting index and contralateral SBCs and has a potential role in detecting contralateral SBCs which are smaller than that of index cancers in heterogeneously dense and dense breasts.

Reviewer’s Comments
The prognosis of bilateral SBCs is worse than that of unilateral breast cancers. According to recent literature, the incidence of mammographically and clinically occult bilateral SBCs detected on MRI of the breast range from 3% to 11%.

However, MRI of the breast has some drawbacks in comparison to whole-breast US, including being more expensive, usually requiring more time to perform, and requiring IV contrast injection which is associated with rare but significant nephrotoxicity, such as nephrogenic systemic fibrosis. Sampling of MRI-detected lesions requires a dedicated MRI-compatible biopsy unit and usually requires a longer time.

It is important to detect bilateral SBCs at the time of initial diagnosis of the index cancer, and the results of this study suggest a potential role of whole-breast US in detecting contralateral SBCs.

Author: Bokran Won, MD

Reference:
Kim MJ, Kim EK, et al. Bilateral Synchronous Breast Cancer in an Asian Population: Mammographic and Sonographic Characteristics, Detection Methods, and Staging. AJR Am J Roentgenol; 2008; 190 (January): 200-213