Tailor-made Surgery of the Axilla in Breast Cancer Patients with Microinvasive Disease or Ductal Carcinoma In Situ
Author: Emil Villiam Holm-Rasmussen, MD, PhD
Supervisors: Eva Balslev, MD, Tove Filtenborg Tvedskov, MD, PhD, DMSc and Niels Kroman, Professor, MD, DMSc
Date, Institution and University: 2019, Department of Breast Surgery, Copenhagen University Hospital
Nationwide mammographic screening has increased the number of women diagnosed with early stage breast cancers; microinvasive breast cancer (<1mm, MIBC) and non-invasive ductal carcinoma in situ (DCIS). MIBC rarely metastasizes and theoretically DCIS does not have a metastatic potential. However, to some extent, lymphatic spread to the axillary lymph nodes has been reported in both groups. Occult cancer or iatrogenic tumor cell displacement might cause lymph node metastases in patients with DCIS. Due to the low risk of lymph node metastases in patients with MIBC and DCIS the use of sentinel lymph node (SN) biopsy (SLNB) and/or axillary lymph node dissection (ALND) has been debated. SLNB causes less morbidity compared to ALND. Nevertheless, side effects such as lymphedema, arm/shoulder pain and impaired movement of the arm/shoulder have been reported after SLNB. If we can identify patients with MIBC or DCIS in high risk of lymph node metastases, tailor-made axillary surgery can be offered and overtreatment can be avoided.
The use of SLNB in Danish women with DCIS is based on national guidelines. The compliance with the guidelines has never been examined in Denmark. In the present thesis, we have used data from the Danish Breast Cancer Group (DBCG) to examine the subject. The thesis showed a considerable variation in the use of SLNB in DCIS patients treated by breast conserving surgery (BCS) among Danish breast surgery departments. The department volume had an impact on the use of SLNB. SLNB was used more frequently with BCS at low-volume departments compared to high-volume departments. In contrast, SLNB was used more frequently with mastectomy at high-volume departments compared to low-volume departments. This indicates a higher compliance with the national SLNB guidelines in Danish DCIS patients at high-volume departments compared to low-volume departments.
In the present thesis, data from the DBCG was also used to examine the rate and risk factors of SN-metastases and the rate of non-SN metastases (NSN) in women with DCIS and MIBC.
Of patients with DCIS, 4% had SN metastases. NSN metastases were detected in less than 10%. However, 23% of DCIS patients with SN macrometastases also had NSN metastases which indicates occult cancer of the breast. These patients should be offered an ALND. SN-metastases were associated with a younger age (≤49 years), DCIS size, (≥50 mm), palpability and preoperative surgical excisional biopsy. Surgical excisional biopsy was associated with the presence of isolated tumor cells in the SN and to some extent SN micrometastases. This indicates iatrogenic displacement of tumor cells without any metastatic potential. Accordingly, these patients should not be upstaged, nor treated as invasive carcinoma.
Of patients with MIBC, 22% had SN metastases. Less than 4% had SN macrometastases of which 22% had NSN metastases. Primarily, SN metastases were found in younger patients (≤49 years) and/or patients with HER2+ MIBC. To avoid overtreatment, axillary staging is not recommended in older (≥50 years) HER2─ MIBC patients without axillary staging at primary surgery. Still, axillary staging should be confined to younger HER2+ MIBC patients without axillary staging at primary surgery.