The aim of this thesis was to address pitfalls and concerns of the diagnostic evaluation of nonpalpable breast lesions, in an attempt to further improve preoperative diagnostic assessment, as well as surgical strategies of nonpalpable breast lesions.
Chapter 1 presents an overview of current methods in preoperative diagnostic assessment and treatment of nonpalpable breast lesions. Results of stereotactic large-core needle biopsy (SLCNB) in current practice (2000-2002) are described and compared to results of the controlled study setting during COBRA ( COre Biopsy after RAdiological localisation; 1997-2000) in chapter 2. Data on all (n=955) patients scheduled to undergo SLCNB in current practice was assembled. At follow-up of women with benign diagnoses at SLCNB who no longer needed to undergo surgical excision, we found that no malignancies were missed. The follow-up was, however, limited (mean, 20.0 months; 5.8-34.0). 96% of patients was treated according to COBRA guidelines.
In chapter 3, we studied differences in cancer prevalence between women referred through the national screening program and a non-screening group, to assess whether the validity of SLCNB differed between these patient groups. The prevalence of carcinoma differed significantly, yet the accuracy of SLCNB did not. Therefore SLCNB appears accurate in diagnosing nonpalpable breast lesions both in screening and non-screening patients.
In chapter 4, we describe a subgroup of lesions for which surgical excision with SNB may be considered as the first diagnostic and therapeutic procedure. SLCNB is preferred in all other cases.
Seeding of biopsy needle tracks with viable malignant cells is evaluated in chapter 5. We conclude that needle tracks can be found, and displaced tumourcells can be recognised. Excising and evaluating the entire needle track is not always possible, should not be recommended as a routine, since radiotherapy is advised for all types of locally excised breast cancer.
When ductal carcinoma in situ (DCIS) is diagnosed at SLCNB, invasive cancer is found in ~17% of excision specimens. These so called 'DCIS-underestimates' generally cause extension of treatment. In chapter 6, we evaluated DCIS-underestimates in detail and assessed reasons for missing the invasive component at SLCNB. A variety of radiological and histopathological reasons contribute to the DCIS-underestimate rate. Approximately half of these are potentially avoidable.
Chapter 7 presents a critical review of the currently available literature on the accuracy of vacuum-assisted biopsy and compare it to published data on 14G automated-needle biopsy.
Chapter 8 describes the surgical treatment results for patients diagnosed with DCIS at SLCNB. We sought preoperative determinants predicting which patients would eventually undergo mastectomy. These determinants were a history of breast cancer, mammographic lesions characterised by calcifications, measuring >17mm and classified as BI-RADS 5. Knowledge of these determinants may guide the initial surgical procedure to be more aggressive.
In Chapter 9 we compared the outcomes of surgical treatment of nonpalpable breast cancer diagnosed preoperatively with SLCNB in two surgical training hospitals, and conclude that with adequate supervision, the experience of the first operating surgeon does not seem to affect the possibility of a radical resection.
Chapter 10 is a general discussion.