Cancer Causes & Control

, Volume 20, Issue 5, pp 663–670

Season of diagnosis and prognosis in breast and prostate cancer

  • Lars Holmberg
  • Jan Adolfsson
  • Lorelei Mucci
  • Hans Garmo
  • Hans Olov Adami
  • Henrik Möller
  • Jan-Erik Johansson
  • Meir Stampfer
Original Paper

DOI: 10.1007/s10552-008-9279-6

Cite this article as:
Holmberg, L., Adolfsson, J., Mucci, L. et al. Cancer Causes Control (2009) 20: 663. doi:10.1007/s10552-008-9279-6

Abstract

Background

Patients with breast or prostate cancer diagnosed during the summer season have been observed to have better survival. The extent to which this is due to biological and/or health care system related factors is unclear.

Methods

Using the Swedish Cancer Register and clinical databases, we analyzed overall survival by month of diagnosis among the incident cases of breast (n = 89,630) cancer and prostate (n = 72,375) cancer diagnosed from 1960 to 2004. We retrieved data on tumor stage from 1976 for breast cancer and 1997 for prostate cancer. Cox proportional hazards models were used to calculate relative risk of survival by the season of diagnosis.

Results

There was a higher hazard ratio of death in men and women diagnosed with cancer in the summer with a relative hazard of 1.20 (95% confidence interval 1.15–1.25) for July for prostate cancer and 1.14 (95% confidence interval 1.09–1.19) for August for breast cancer when compared to being diagnosed in January. This difference coincided with a lower mean number of cases diagnosed per day, and a higher proportion of advanced cases diagnosed in the summer. This pattern of presentation was stronger in the later years.

Conclusion

The difference in stage distribution explains the seasonal variation in prognosis seen in this study. The variation may be because of structure of the health care system and a strong tradition of vacationing from mid June to mid August. Thus, the health care infrastructure and the late presentation of symptomatic disease may influence cancer survival studied by season of diagnosis substantially.

Keywords

Breast cancerProstate cancerPrognosisSeason of diagnosisEarly diagnosis

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Lars Holmberg
    • 1
    • 2
  • Jan Adolfsson
    • 3
  • Lorelei Mucci
    • 4
    • 5
  • Hans Garmo
    • 1
    • 2
  • Hans Olov Adami
    • 5
  • Henrik Möller
    • 2
  • Jan-Erik Johansson
    • 6
  • Meir Stampfer
    • 4
    • 5
  1. 1.Regional Oncologic Center and Department of Surgical SciencesUppsala UniversityUppsalaSweden
  2. 2.Division of Cancer Studies, Medical SchoolKing’s College LondonLondonUK
  3. 3.Oncologic CenterCLINTEC, Karolinska InstituteStockholmSweden
  4. 4.Channing Laboratory, Department of MedicineBrigham and Women’s Hospital and Harvard Medical SchoolBostonUSA
  5. 5.Department of EpidemiologyHarvard School of Public HealthBostonUS
  6. 6.Center for Assessment of Medical TechnologyÖrebro University HospitalÖrebroSweden