Factors associated with arm swelling in patients undergoing surgery and radiotherapy for breast cancer within the FAST-Forward trial nodal sub-study.

PURPOSE/

OBJECTIVE

The FAST-Forward randomised nodal sub-study primary analysis showed non-inferiority for 5-year patient-reported arm/hand swelling following adjuvant breast/chest wall and axillary radiotherapy given in 26 Gy in 5 fractions (Fr) over 1 week compared to 40 Gy in 15Fr over 3 weeks. This subsequent analysis investigates the association between patient, tumour and treatment factors and development of long-term arm/hand swelling.

MATERIAL/

METHODS

Data from 469 patients randomised to adjuvant radiotherapy 40 Gy/15Fr, 27 Gy/5Fr or 26 Gy/5Fr to breast/chest wall and axilla (any or all levels 1-4) in the FAST-Forward nodal sub-study were included. DICOM-RT data were collected prospectively. ESTRO-defined axillary nodal levels 1-4, the axillary-lateral thoracic vessel juncture (ALTJ), and visible seroma were contoured retrospectively. Mean, maximum and minimum doses were extracted. Univariable and stepwise multivariable logistic regression were used to identify predictors of 5-year arm swelling.

RESULTS

At 5 years, moderate/marked arm/hand swelling was reported by 39/299 (13%) patients and clinician-reported arm lymphoedema by 45/346 (13%). Multivariable analysis identified axillary lymph node dissection (ALND) (OR 3.70, 95% CI [1.61-8.48], p = 0.002) and BMI ≥ 35 kg/m2 (OR 3.31 [1.08-10.12], p = 0.036) as significant predictors of 5-year patient-reported moderate/marked arm/hand swelling. For 5-year clinician-reported arm lymphoedema, multivariable analysis identified ALND (OR 3.67 [1.55-8.69], p = 0.003) and number of positive lymph nodes (OR 1.08 [1.00-1.18], p = 0.049) as significant predictors. No significant associations were found between individual dosimetric parameters and 5-year arm swelling on multivariable analysis.

CONCLUSION

Axillary surgery remains the main predictor of long-term arm lymphoedema following locoregional radiotherapy for node-positive breast cancer, supporting de-escalation of ALND to reduce this risk.