Clinical impact of MRI-detected additional lesions in breast cancer patients with neoadjuvant systemic therapy at the Netherlands cancer institute.

BACKGROUND: In breast cancer patients treated with neoadjuvant systemic therapy (NST), MRI is used pre- and post-NST for response monitoring. The relevance of additional MRI-detected lesions in these patients is unclear. Therefore, we aimed to assess the impact of pre-NST MRI-detected additional lesions on surgical treatment and outcome. METHODS: We retrospectively selected all early-stage breast cancer patients with MRI pre-NST at our institute from January 2010-2015. MRI-detected lesions were defined as separated from the index tumor and occult at conventional mammography and ultrasound. Outcomes were change in surgical treatment and five-year recurrence-free and overall survival. RESULTS: Overall, MRI detected additional lesions in 206 (31%) of 656 patients: in 160 patients in the ipsilateral breast and in 78 contralateral breasts, including 32 bilateral cases. Ipsilateral lesions were mostly categorized BI-RADS 5 (54 %) and contralateral lesions BI-RADS 3 (64%). Targeted ultrasound was performed in 115 (56%) patients: in 70 ipsilateral and in 64 contralateral cases. Biopsy was obtained in 44 (28% of 160) ipsilateral and 50 (64% of 78) contralateral breasts, containing tumor foci in 20 (13% of 160) and 11 (14% of 78) cases, respectively. Surgical treatment changed in 54 (26% of 206) patients: 19 (9%) had mastectomy, 24 (12%) had wider local excision and 11 (5%) underwent contralateral surgery. Five-year recurrence-free and overall survival did not differ for patients with local excision or mastectomy. CONCLUSION: Pre-NST MRI-detected additional lesions in 31% of patients, resulting in more extensive surgery in 26% of these patients, including 5% contralateral surgeries.

Finding the balance between over- and under-treatment of ductal carcinoma in situ (DCIS).

With the widespread adoption of population-based breast cancer screening, ductal carcinoma in situ (DCIS) has come to represent 20-25% of all breast neoplastic lesions diagnosed. Current treatment aims at preventing invasive breast cancer, but the majority of DCIS lesions will never progress to invasive disease. Still, DCIS is treated by surgical excision, followed by radiotherapy as part of breast conserving treatment, and/or endocrine therapy. This implies over-treatment of the majority of DCIS, as less than 1% of DCIS patients will go on to develop invasive breast cancer annually. If we are able to identify which DCIS is likely to progress or recur as invasive breast cancer and which DCIS would remain indolent, we can treat the first group intensively, while sparing the second group from such unnecessary treatment (surgery, radiotherapy, endocrine therapy) preserving the quality of life of these women. This review summarizes our current knowledge on DCIS and the risks involved regarding progression into invasive breast cancer. It also shows current knowledge gaps, areas where profound research is highly necessary for women with DCIS to prevent their over-treatment in case of a harmless DCIS, but provide optimal treatment for potentially hazardous DCIS.

[Ductal carcinoma in situ: the balance between over- and undertreatment]. / Ductaal carcinoma in situ: de balans tussen over- en onderbehandeling.

Since population-based breast cancer screening was implemented in the Netherlands, the incidence of Ductal Carcinoma In Situ of the breast, regarded as a non-obligate precursor lesion of breast cancer, has strongly increased. However, the incidence of invasive breast cancer has not decreased. This suggests that a percentage of all the DCIS lesions would never have become symptomatic if no screening was performed. This phenomenon is known as 'overdiagnosis'. Nonetheless, almost all DCIS lesions are managed surgically, often followed by radiotherapy in those having breast-conserving treatment, to avoid potential progression to breast cancer. To prevent potential over- or undertreatment, further studies are required to distinguish low from high risk DCIS. Ultimately this could help avoid non-beneficial intensive treatment for women with low risk DCIS.