Herpes zoster in breast cancer patients after radiotherapy

We have studied the incidence of herpes zoster in patients with adjuvant radiotherapy for breast cancer with special emphasis on possible correlations with other prognostic factors or survival.

From 1/1985 through 12/1993, 1,155 breast cancer patients received postoperative radiotherapy with curative intent in our department. After mastectomy 961 patients were irradiated and after breast-preserving treatment 194 patients. The age ranged from 34 to 79 years, the median follow-up was 3.1 years (range: 0.3 to 12.4 years). There were 443 women (38%) pre- and 712 (62%) postmenopausal. 21% had T3- to T4-tumors, 55% had axillary lymph node involvement, and 65% received additional systemic hormonal and/or cytotoxic therapy. In case of postmastectomy radiotherapy, the lateral chest wall and lymphatics (axilla, parasternal and supraclavicular nodes) were irradiated with an anterior photon field to 50 Gy (axilla 44 Gy) and most of the chest wall with an electron field to 44 Gy in 2-Gy fractions. After breast-preservation, the breast was irradiated via tangential fields with 6- to 8-MV photons up to 50 Gy plus 8 Gy electron boost to the tumor bed. Most of the patients were followed routinely in the department for 2 to 5 years. The frequency of zoster was determined retrospectively by reviewing the patients' records.

A zoster after radiotherapy occurred in 41/1,155 patients (3.7%), mostly within the first 2 years after completion of radiotherapy. All infections remained localized and there was no evidence for systemic infections. Type of treatment (mastectomy vs breast-preservation) had no impact on the frequency of herpes zoster (36/961 patients after mastectomy and 5/194 patients after breast-preservation). There was also no correlation with other prognostic factors such as age, menopausal status, stage of disease or the use of adjuvant chemotherapy, nor was the occurrence of zoster linked to the degree of acute skin reaction in the radiation field. Moreover, patients with zoster had the same prognosis as compared to patients without zoster with regard to local control and survival.

The observed frequency of zoster (about 4% of patients after postoperative radiotherapy) in this retrospective study suggests that the risk of developing zoster in this patient group may be 3- to 5-fold higher as compared to the incidence in the general population. However, the occurrence of zoster was not linked to prognosis and treatment response.