After 1 year, more than 50% experience upper limb (UL) complaints after treatment for breast cancer. These complaints are disabling and cause limitations in daily life and this leads to a decrease in the patient's quality of life. The cause of these UL complaints is complex and multifactorial. Due to breast cancer treatment, the structural (tissue composition and volume) and mechanical (tissue stiffness) properties of the soft tissue may change. These changes can occur in the muscle, skin and surrounding fascia and especially in the soft tissue around the breast and axilla where that treatment is localised.

Ultrasound with specific 'add-on' techniques can objectively assess these features and provide a picture of their role in UL function after breast cancer. The first aim in this study is to investigate the reliability and validity of conventional 2D ultrasound for 1) soft tissue composition and 2) soft tissue thickness at the level of the breast and upper limb. The reliability and validity of shear wave elastography, a specific complement to conventional 2D ultrasound, to assess tissue stiffness will also be examined.

1. Breast cancer patients without upper limb dysfunctions (n=30) Inclusion Criteria

   • Patients with unilateral primary breast cancer
   • Surgery including, either: Mastectomy with axillary lymph node dissection or sentinel lymph node biopsy or breast conserving surgery with axillary lymph node dissection or sentinel lymph node biopsy
   • At least 3 months after surgery or radiotherapy in order to take into account wound healing
   • Comprehensive of the Dutch language
   • QuickDASH score <15/100

   Exclusion Criteria:

   • Bilateral surgery, widespread distance metastases, previous breast surgery
   • Diagnosis of neurological or rheumatological condition
   • upper limb dysfunctions caused by other reasons

2. Breast cancer patients with upper limb dysfunctions (n=30) Inclusion Criteria

   • Patients with unilateral primary breast cancer
   • Surgery including, either: Mastectomy with axillary lymph node dissection or sentinel lymph node biopsy or breast conserving surgery with axillary lymph node dissection or sentinel lymph node biopsy
   • At least 3 months after surgery or radiotherapy in order to take into account wound healing
   • Comprehensive of the Dutch language
   • QuickDASH score >15/100

   Exclusion Criteria:

   • Bilateral surgery, widespread distance metastases, previous breast surgery
   • Diagnosis of neurological or rheumatological condition
   • upper limb dysfunctions caused by other reasons

3. Healthy volunteers (n=30)

Inclusion criteria:

• Healthy women (QuickDASH <15) age-matched with a breast cancer patient from the main study
• Comprehensive of the Dutch language

Exclusion criteria:

• upper limb dysfunctions
• Diagnosis of neurological or rheumatological condition, diabetes

Women with history of primary breast cancer

Women with a history of primary breast cancer with and without upper limb dysfunctions and an age- and gender-matched healthy control group