title: Menstrual cycle and surgical treatment of breast cancer: findings from the NCCTG N9431 study.
abstract: OBJECTIVE
  For nearly two decades, multiple retrospective reports, small prospective studies, and meta-analyses have arrived at conflicting results regarding the value of timing surgical intervention for breast cancer on the basis of menstrual cycle phase. We present the results of a multi-cooperative group, prospective, observational trial of menstrual cycle phase and outcome after breast cancer surgery, led by the North Central Cancer Treatment Group (NCCTG) in collaboration with the National Surgical Adjuvant Breast and Bowel Project (NSABP) and the International Breast Cancer Study Group (IBCSG).
  
  
  METHODS
  Premenopausal women age 18 to 55 years, who were interviewed for menstrual history and who were surgically treated for stages I to II breast cancer, had serum drawn within 1 day of surgery for estradiol, progesterone, and luteinizing hormone levels. Menstrual history and hormone levels were used to determine menstrual phase: luteal, follicular, and other. Disease-free survival (DFS) and overall survival (OS) rates were determined by Kaplan-Meier method and were compared by using the log-rank test and Cox proportional hazard modeling.
  
  
  RESULTS
  Of 1,118 women initially enrolled, 834 women comprised the study cohort: 230 (28%) in luteal phase; 363 (44%) in follicular phase; and 241 grouped as other. During a median follow-up of 6.6 years, and in analysis that accounted for nodal disease, estrogen receptor status, adjuvant radiation therapy or chemotherapy, neither DFS nor OS differed with respect to menstrual phase. The 5-year DFS rates were 82.7%, 82.1%, and 79.2% for follicular, luteal, or other phases, respectively. Corresponding OS survival rates were 91.9%, 92.2%, and 91.8%, respectively.
  
  
  CONCLUSIONS
  When menstrual cycle phases were strictly defined, neither DFS nor OS differed between women who underwent surgery during the follicular phase versus the luteal phase. Nearly 30% of the patients did not meet criteria for either follicular- or luteal-phase categories.
authors.affiliation: Division of General Surgery, Mayo Clinic, North Central Cancer Treatment Group, Dept of Surgery, 200 1st St SW, Rochester, MN 55905, USA. cgrant@mayo.edu
authors.forename: Clive S
authors.initials: CS
authors.lastname: Grant
authors.forename: James N
authors.initials: JN
authors.lastname: Ingle
authors.forename: Vera J
authors.initials: VJ
authors.lastname: Suman
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Dumesic
authors.forename: D Lawrence
authors.initials: DL
authors.lastname: Wickerham
authors.forename: Richard D
authors.initials: RD
authors.lastname: Gelber
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Flynn
authors.forename: Lorna M
authors.initials: LM
authors.lastname: Weir
authors.forename: Mattia
authors.initials: M
authors.lastname: Intra
authors.forename: Wayne O
authors.initials: WO
authors.lastname: Jones
authors.forename: Edith A
authors.initials: EA
authors.lastname: Perez
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Hartmann
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000097:blood / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D018572:Disease-Free Survival; D005498:Follicular Phase / Q000097:blood*; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008183:Luteal Phase / Q000097:blood*; D008297:Male; D008408:Mastectomy / Q000379:methods* / Q000401:mortality; D008597:Menstrual Cycle / Q000097:blood; D008875:Middle Aged; D009367:Neoplasm Staging; D017697:Premenopause; D011300:Preoperative Care / Q000379:methods; D011336:Probability; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult