Explaining Socioeconomic Status Effects in Laryngeal Cancer

Groome, P.A.; Schulze, K.M.; Keller, S.; Mackillop, W.J.; O'Sullivan, B.; Irish, J.C.; Bissett, R.J.; Dixon, P.F.; Eapen, L.J.; Gulavita, S.P.P.; Hammond, J.A.; Hodson, D.I.; Mackenzie, R.G.; Schneider, K.M.; Warde, P.R.

doi:10.1016/j.clon.2005.12.010

« Previous Next »Clinical Oncology
Volume 18, Issue 4 , Pages 283-292, May 2006

Explaining Socioeconomic Status Effects in Laryngeal Cancer

P.A. Groome
- Division of Cancer Care and Epidemiology, Queen's Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
- Author for correspondence: Patti A. Groome, PhD, Division of Cancer Care and Epidemiology, Queen's University Cancer Research Institute, 10 Stuart Street, 2nd level, Kingston, Ontario K7L 3N6, Canada. Tel: +1-613-533-6000 ext 78512; Fax: +1-613-533-6794
K.M. Schulze
- Division of Cancer Care and Epidemiology, Queen's Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
S. Keller
- Division of Cancer Care and Epidemiology, Queen's Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
W.J. Mackillop
- Division of Cancer Care and Epidemiology, Queen's Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
B. O'Sullivan
- Princess Margaret Hospital and University of Toronto, Toronto, Ontario, Canada
J.C. Irish
- Princess Margaret Hospital and University of Toronto, Toronto, Ontario, Canada
R.J. Bissett
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
P.F. Dixon
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
L.J. Eapen
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
S.P.P. Gulavita
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
J.A. Hammond
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
D.I. Hodson
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
R.G. Mackenzie
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
K.M. Schneider
- Departments of Radiation Oncology at the Regional Cancer Centres of Cancer Care Ontario, Ontario, Canada
P.R. Warde
- Princess Margaret Hospital and University of Toronto, Toronto, Ontario, Canada

Received 11 November 2004; received in revised form 19 October 2005; accepted 16 December 2005.

Abstract

Introduction

People with lower socioeconomic status (SES) experience shorter survival times after a cancer diagnosis for many disease sites. We determined whether area-level SES was associated with the outcomes: cause-specific survival and local-regional failure in laryngeal cancer in Ontario, Canada. When we found an association we sought explanations that might be related to access to care including age, sex, rural residence, tumor stage, lymph node status, use of diagnostic imaging, treatment type, percentage of prescribed radiotherapy delivered, number of radiotherapy interruption days, treatment waiting time, and treating cancer center.

Materials and Methods

The study population consisted of 661 glottic and 495 supraglottic stage-stratified randomly-sampled patients identified using the Ontario Cancer Registry. Area-level SES quintiles were assigned using adjusted median household income from the Canadian Census. Other data were collected from patient charts. Explanations for SES effects were determined by measuring whether the effect moved toward the null value by at least 10% when an access indicator was added to a the model.

Results

Socioeconomic status was not related to either outcome for those with supraglottic cancer, but an association was present in glottic cancer. With the highest socioeconomic status quintile as the referent group, the relative risks for patients in the lowest socioeconomic quintile were 2.75 (95% CI 1.48, 5.12) for cause-specific survival and 1.90 (95% CI 1.24, 2.93) for local-regional failure. Disease stage as measured by T-category explained between 3% and 23% of these socioeconomic effects. None of the other access indicators met our 10% change criterion.

Conclusion

We question why people in lower socioeconomic quintiles were not diagnosed earlier in the disease progression. Having ruled out several variables that may be related to access to care, additional biologic and social variables should be examined to further understand socioeconomic status effects.

Key words: Access to care, laryngeal cancer, population-based, socioeconomic status, survival