Radiation Therapy to the Plexus Brachialis in Breast Cancer Patients: Analysis of Paresthesia in Relation to Dose and Volume.

PURPOSE: To identify volume and dose predictors of paresthesia after irradiation of the brachial plexus among women treated for breast cancer.

METHODS AND MATERIALS: The women had breast surgery with axillary dissection, followed by radiation therapy with (n=192) or without irradiation (n=509) of the supraclavicular lymph nodes (SCLNs). The breast area was treated to 50 Gy in 2.0-Gy fractions, and 192 of the women also had 46 to 50 Gy to the SCLNs. We delineated the brachial plexus on 3-dimensional dose-planning computerized tomography. Three to eight years after radiation therapy the women answered a questionnaire. Irradiated volumes and doses were calculated and related to the occurrence of paresthesia in the hand.

RESULTS

After treatment with axillary dissection with radiation therapy to the SCLNs 20% of the women reported paresthesia, compared with 13% after axillary dissection without radiation therapy, resulting in a relative risk (RR) of 1.47 (95% confidence interval [CI] 1.02-2.11). Paresthesia was reported by 25% after radiation therapy to the SCLNs with a V40 Gy ≥ 13.5 cm(3), compared with 13% without radiation therapy, RR 1.83 (95% CI 1.13-2.95). Women having a maximum dose to the brachial plexus of ≥55.0 Gy had a 25% occurrence of paresthesia, with RR 1.86 (95% CI 0.68-5.07, not significant).

CONCLUSION

Our results indicate that there is a correlation between larger irradiated volumes of the brachial plexus and an increased risk of reported paresthesia among women treated for breast cancer.