title: Pre-treatment platelet counts as a prognostic and predictive factor in stage II and III rectal adenocarcinoma.
abstract: OBJECTIVE
  To investigate if pre-treatment platelet counts could provide prognostic information in patients with rectal adenocarcinoma that received neo-adjuvant treatment.
  
  
  METHODS
  Platelet number on diagnosis of stage II and III rectal cancer was evaluated in 51 patients receiving neo-adjuvant treatment and for whom there were complete follow-up data on progression and survival, as well as pathologic outcome at the time of surgery. Pathologic responses on the surgical specimen of patients with lower platelet counts (150-300 × 109/L) were compared with these of patients with higher platelet counts (> 300 × 109/L) by theχ2test. Overall and progression free survival Kaplan-Meier curves of the two groups were constructed and compared with the Log-Rank test.
  
  
  RESULTS
  A significant difference was present between the two groups in regards to pathologic response with patients with lower platelet counts being more likely to exhibit a good or complete response to neo-adjuvant treatment than patients with higher platelet counts (P= 0.015). Among other factors evaluated, there was also a significant difference between the carcinoembryonic antigen (CEA) at presentation of patients that exhibited a good or complete response and those that had no response or a minimal to moderate response. Patients with a good or complete response were more likely to present with a CEA of less than 5 μg/L (P =0.00066). There was no significant difference in overall and progression free survival between the two platelet count groups (Log-Rank testsP= 0.42 andP= 0.35, respectively).
  
  
  CONCLUSIONS
  In this retrospective analysis of stage II and III rectal cancer patients, platelet counts at the time of diagnosis had prognostic value for neo-adjuvant treatment pathologic response. Pre-treatment CEA also held prognostic value in regards to treatment effect.
authors.affiliation: Morgan Steele, Clinical Trials Unit, Sault Area Hospital, Sault Ste Marie, Ontario P6B 0A8, Canada.
authors.forename: Morgan
authors.initials: M
authors.lastname: Steele
authors.affiliation: Morgan Steele, Clinical Trials Unit, Sault Area Hospital, Sault Ste Marie, Ontario P6B 0A8, Canada.
authors.forename: Ioannis A
authors.initials: IA
authors.lastname: Voutsadakis
keywords: Chemoradiation; Neo-adjuvant; Platelets; Prognosis; Rectal cancer; Treatment response