“Association of Radiation-induced Lymphocyte Apoptosis with Radiation Induced Fibrosis after Breast Conserving Therapy”

Around 5% of all patients treated with breast conserving therapy (BCT) are affected by a severe form of radiation-induced fibrosis (RIF) of the treated breast. RIF is characterized by reduced tissue flexibility, reduced compliance or stricture. There is a large patient-to-patient variability of being at risk for RIF. The severity of RIF is known to be affected by differences in treatment characteristics and individual radiosensitivity. An important biological difference associated with differences in individual radiosensitivity, is the presence of senescence in cells. Senescence is a permanent arrest state of the cell division. Senescence can be induced by Ionizing Radiotherapy (IR) in fibroblasts and other cellular types. The senescence characteristic of reduced apoptosis can possibly be used to assess the risk of RIF. The risk of RIF was reported to show a positive correlation with reduced apoptosis in the Radiation-Induced Lymphocyte Apoptosis (RILA) assay. Previous studies have shown that a low RILA frequency is associated with a higher risk of developing RIF. The Primary objective of this study is to assess the univariate association between RILA frequency and RIF after BCT among breast cancer patients. We hypothesize that among breast cancer patients with a grade 3 breast fibrosis the RILA frequency is significantly lower compared to the RILA frequency among breast cancer patients with no fibrosis.

We hypothesize that among breast cancer patients with a grade 3 breast fibrosis the RILA frequency is significantly lower compared to the RILA frequency among breast cancer patients with no fibrosis.

After inclusion, patients will be invited for a one-off hospital visit for blood withdrawal, skin punch biopsy and questionnaires.

• Two 5-ml heparinized blood samples
• Skin punch biopsy
• Three HRQoL questionnaires (BREAST-Q, postoperative BCT module; EORTC QLQ-C30 and BR23)