title: Risk factors of developing long-lasting breast pain after breast cancer radiotherapy.
abstract: OBJECTIVE
  Postoperative radiotherapy decreases breast cancer mortality. However, studies have revealed a long-lasting breast pain among some women after radiotherapy. The purpose of this study was to identify risk factors that contribute to breast pain after breast cancer radiotherapy.
  
  
  METHODS
  We identified 1,027 recurrence-free women in two cohorts of Swedish women treated for breast cancer. The women had breast-conserving surgery and postoperative radiotherapy, the breast was treated to 48 Gy in 2.4-Gy fractions or to 50 Gy in 2.0-Gy fractions. Young women received a boost of up to 16 Gy. Women with more than three lymph node metastases had locoregional radiotherapy. Systemic treatments were given according to health-care guidelines. Three to 17 years after radiotherapy, we collected data using a study-specific questionnaire. We investigated the relation between breast pain and potential risk modifiers: age at treatment, time since treatment, chemotherapy, photon energy, fractionation size, boost, loco-regional radiotherapy, axillary surgery, overweight, and smoking.
  
  
  RESULTS
  Eight hundred seventy-seven women (85%) returned the questionnaires. Among women up to 39 years of age at treatment, 23.1% had breast pain, compared with 8.7% among women older than 60 years (RR 2.66; 95% CI 1.33-5.36). Higher age at treatment (RR 0.96; 95% CI 0.94-0.98, annual decrease) and longer time since treatment (RR 0.93; 95% CI 0.88-0.98, annual decrease) were related to a lower occurrence of breast pain. Chemotherapy increased the occurrence of breast pain (RR 1.72; 95% CI 1.19-2.47). In the multivariable model only age and time since treatment were statistically significantly related to the occurrence of breast pain. We found no statistically significant relation between breast pain and the other potential risk modifiers.
  
  
  CONCLUSIONS
  Younger women having undergone breast-conserving surgery with postoperative radiotherapy report a higher occurrence of long-lasting breast pain compared to older women. Time since treatment may decrease the occurrence of pain.
authors.affiliation: Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden. dan.lundstedt@vgregion.se
authors.forename: Dan
authors.initials: D
authors.lastname: Lundstedt
authors.forename: Magnus
authors.initials: M
authors.lastname: Gustafsson
authors.forename: Gunnar
authors.initials: G
authors.lastname: Steineck
authors.forename: Per
authors.initials: P
authors.lastname: Malmström
authors.forename: David
authors.initials: D
authors.lastname: Alsadius
authors.forename: Agnetha
authors.initials: A
authors.lastname: Sundberg
authors.forename: Ulrica
authors.initials: U
authors.lastname: Wilderäng
authors.forename: Erik
authors.initials: E
authors.lastname: Holmberg
authors.forename: Karl-Axel
authors.initials: KA
authors.lastname: Johansson
authors.forename: Per
authors.initials: P
authors.lastname: Karlsson
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015182:Lymphatic Irradiation; D015412:Mastectomy, Segmental; D059373:Mastodynia / Q000209:etiology*; D008875:Middle Aged; D050177:Overweight / Q000150:complications; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D011795:Surveys and Questionnaires; D013548:Sweden
chemical_list: D000970:Antineoplastic Agents