Probably benign breast masses diagnosed by sonography: is there a difference in the cancer rate according to palpability?

OBJECTIVE: The study was designed to assess retrospectively whether there is a difference in the cancer rates between palpable and nonpalpable probably benign breast nodules detected by sonography. We further investigated the clinicopathologic results of sonographically false-negative cases.

MATERIALS AND METHODS: This study included 352 women who had undergone sonographically guided core biopsies for 374 BI-RADS category 3 masses between March 2004 and February 2005. No masses were diagnosed with definite malignant findings on mammography. The cancer rates of nonpalpable and palpable masses were compared using Fisher's exact test. The clinicopathologic results of sonographically false-negative cases were investigated.

RESULTS: Among the 374 masses, 86 masses (23%) that were lost to follow-up were excluded. Of the 288 masses with follow-up or excision, the cancer rate was 2.4% (7/288). The cancer rate of the nonpalpable masses was 2.1% (4/194) (95% CI, 0.6-5.2%), and the cancer rate of the palpable masses was 3.2% (3/94) (95% CI, 0.6-9.0%), with no statistically significant difference (p = 0.6864). Of the seven cancers, five were diagnosed by a sonographically guided core biopsy and two were diagnosed by surgical excision after a benign biopsy. The seven sonographically false-negative masses in seven patients were identified as three invasive ductal carcinomas, two ductal carcinomas in situ, one mucinous carcinoma, and one papillary carcinoma on the basis of pathology results.

CONCLUSION: There is no statistically significant difference between the cancer rates of palpable and nonpalpable BI-RADS category 3 masses seen on sonography.