Cancer Survival by Stage at Diagnosis in Kuwait: A Population-Based Study

Abstract

Objective. To examine the distribution of stage at diagnosis for 12 cancers in Kuwait, to estimate stage-specific net survival at 1 and 5 years after diagnosis, and to assess differences in stage-specific survival between Kuwait and the United States. Material and Methods. Data were obtained from the Kuwait Cancer Registry, for Kuwaiti patients diagnosed during 2000–2013, with follow-up to 31 December 2015. The distribution of Surveillance Epidemiology and End Results (SEER) Summary Stage for 12 malignancies was examined. We estimated net survival by stage up to 5 years after diagnosis, controlling for background mortality with life tables of all-cause mortality in the general population by single year of age, sex, and calendar period. Survival estimates were age-standardised using the International Cancer Survival Standard (ICSS) weights. Results. Only 14.2% of patients were diagnosed at a localised stage and 38.9% at the regional stage. The proportion of patients with known stage was 88.9% during 2000–2004 but fell to 59.4% during 2010–2013. During 2005–2009, 1- and 5-year survival for colon, rectal, breast, cervical, and prostate cancer was about 90% or higher for patients diagnosed at the localised stage. During 2004–2009, the proportion of patients diagnosed at a localised stage was lower in Kuwait than in the US for colon, breast, and lung cancer. Age-standardised 5-year net survival for all stages combined was lower in Kuwait than the US for colon, lung, and breast cancer, but stage-specific survival was similar. Conclusion. Since stage-specific survival is similar in Kuwait and the US, late stage at diagnosis is likely to be a major contributing factor to the overall lower survival in Kuwait than in the US. Increasing public awareness of cancer risk factors and symptoms and investment in early detection will be vital to reduce the proportion of patients diagnosed at a late stage and to improve survival.