title: Effect of diagnostic delay on survival in patients with colorectal cancer: a retrospective cohort study.
abstract: Disparate and contradictory results make studies necessary to investigate in more depth the relationship between diagnostic delay and survival in colorectal cancer (CRC) patients. The aim of this study is to analyse the relationship between the interval from first symptom to diagnosis (SDI) and survival in CRC.
  
  
  
  Retrospective study of n = 942 CRC patients. SDI was calculated as the time from the diagnosis of cancer and the first symptoms of CRC. Cox regression was used to estimate five-year mortality hazard ratios as a function of SDI, adjusting for age and gender. SDI was modelled according to SDI quartiles and as a continuous variable using penalized splines.
  
  
  
  Median SDI was 3.4 months. SDI was not associated with stage at diagnosis (Stage I = 3.6 months, Stage II-III = 3.4, Stage IV = 3.2; p = 0.728). Shorter SDIs corresponded to patients with abdominal pain (2.8 months), and longer SDIs to patients with muchorrhage (5.2 months) and rectal tenesmus (4.4 months). Adjusting for age and gender, in rectum cancers, patients within the first SDI quartile had lower survival (p = 0.003), while in colon cancer no significant differences were found (p = 0.282). These results do not change after adjusting for TNM stage. The splines regression analysis revealed that, for rectum cancer, 5-year mortality progressively increases for SDIs lower than the median (3.7 months) and decreases as the delay increases until approximately 8 months. In colon cancer, no significant relationship was found between SDI and survival.
  
  
  
  Short diagnostic intervals are significantly associated with higher mortality in rectal but not in colon cancers, even though a borderline significant effect is also observed in colon cancer. Longer diagnostic intervals seemed not to be associated with poorer survival. Other factors than diagnostic delay should be taken into account to explain this "waiting-time paradox".
authors.affiliation: Clinical Epidemiology and Biostatistics Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña, A Coruña, Spain. salvador.pita.fernandez@sergas.es.
authors.forename: Salvador
authors.initials: S
authors.lastname: Pita-Fernández
authors.affiliation: Surgery Department, Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña, A Coruña, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: González-Sáez
authors.affiliation: Clinical Epidemiology and Biostatistics Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña, A Coruña, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: López-Calviño
authors.affiliation: Clinical Epidemiology and Biostatistics Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña, A Coruña, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Seoane-Pillado
authors.affiliation: Department of Population Screening Programs, SERGAS, Santiago de Compostela, A Coruña, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Rodríguez-Camacho
authors.affiliation: Department of Information and Communication Technologies, Computer Science Faculty, University of A Coruña, A Coruña, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Pazos-Sierra
authors.affiliation: Meicende Primary Care Health Centre, SERGAS, A Coruña, Spain.
authors.forename: Paloma
authors.initials: P
authors.lastname: González-Santamaría
authors.affiliation: Clinical Epidemiology and Biostatistics Research Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), SERGAS, Universidade da Coruña, A Coruña, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Pértega-Díaz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000401:mortality*; D057210:Delayed Diagnosis / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D013997:Time Factors
keywords: Colorectal neoplasms; Delayed diagnosis; Mortality; Nonparametric; Statistics; Survival