Short summary

Obese women have a higher risk of breast cancer, harmful effect after surgery and a poorer survival rate. Nodal status is an important prognostic factor for long-term survival. Axillary ultrasound (AUS) combined with fine needle aspiration (FNA) has an accuracy > 70%, but it is unclear if obesity affects the accuracy. Through national registries, the study aim to evaluate a potential association between BMI and the accuracy of AUS/FNA to detect axillary lymph nodes metastasis in breast cancer.

Rationale

The prevalence of obesity is increasing. Evidence suggests that obesity is associated with the development of breast cancer. Obese patients have an increased tumour size and a higher level of axillary involvement compared to normal weight breast cancer patients at the time of diagnosis. This corresponds to the fact that obese breast cancer patients have a higher risk of recurrence and poorer survival. Axillary disease is an important prognostic factor in breast cancer. Approximately 30% of all breast cancer patients have involvement of the axillary lymph nodes. The standard evaluation of the axilla in Denmark is a combination of AUS and fine needle aspiration (FNA) in case AUS reveals any suspicious features of the axillary lymph nodes.

Few studies have examined the effect of obesity on the accuracy of AUS/FNA. Intuitively the identification of suspicious lymph nodes is impaired in obese patient due to increased amount of tissue in the axilla. An American database study of 1510 breast cancer patients evaluated whether BMI affected the accuracy of AUS. Suspicious lymph nodes on AUS was more frequent in patient with a BMI < 25 than > 25. The sensitivity of AUS combined with FNA did not vary across BMI categories. However, specificity was better for overweight and obese patients than normal weight patients. To explain the difference in sensitivity in AUS vs. AUS/FNA they hypothesize, that the normal axillary lymph nodes might be more challenging to identify in obese patient, but that abnormal lymph nodes can still be differentiated.

Correct preoperative evaluation of the axilla is important because it affects the treatment plan. Breast cancer patients with disease in the axillary lymph nodes might be candidates for neoadjuvant therapy. If they after NAT no longer exhibit axillary disease evaluated by sentinel lymph node dissection (SLND), axillary lymph node dissection (ALND) can be avoided. Identification of patients that prosper of additional ALND is essential because ALND has significant higher risk of adverse effects compared with SN, with a higher risk of lymphedema, pain, impaired range of movement and sensory disturbance

The aim of this study is to evaluate a potential association between body mass index and the detection rate of involved axillary lymph nodes by ultrasound and fine needle aspiration in breast cancer patients.

Description of the cohort

Inclusion criteria:

- Danish women > 18 years diagnosed with breast cancer.

- 2010- 2021

Exclusion criteria:

- Previously diagnosed with breast cancer

- Metastatic breast cancer

- Neoadjuvant therapy

Data and biological material

Data from the national registries (National Patient Registry, Danish Clinical Quality Program, Danish Pathology Data Bank, Danish Breast Cancer Group)

Collaborating researchers and departments

Department of Plastic and Breast Surgery Aarhus University Hospital

• Marianne Djernes Lautrup, PhD, Consultant, Clinical lector

Department of Surgery, Vejle Hospital

• Hans B. Rahr, MD, associate professor, Head of Surgery

Department of Clinical Oncology, Regional Hospital Gødstrup

• Troels Bechmann, PhD, Consultant

Department of Breast Surgery, Herlev-Gentofte Hospital

• Tove Tvedskov, Dr. med., PhD, Consultant, Clinical lector

Department of Pathology, Aarhus University Hospital

• Trine Tramm, PhD, Consultant, Clinical lector