EAKAD JA VÄHK – November 2015

Survival of elderly cancer patients in Estonia 2005–2009

Authors: Kaire Innos, Tiiu Aareleid

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In all Western countries, the aging population gives rise to an increasing cancer burden. The increase in the absolute number and proportion of elderly patients crates new challenges for their clinical management. The objective of this study was to examine relative survival for common cancers in Estonia during the period 2005–2009 among patients aged ≥70 years at diagnosis.

The Estonian Cancer Registry provided data on cases of eight common cancers diagnosed in 2000–2008: stomach, colon, rectum, lung, breast, prostate, kidney, urinary bladder. The relative survival ratios (RSR) for the period 2005–2009 were calculated as the ratio of the observed survival of cancer patients to the expected survival of the underlying general population using the period method. The patients were categorized into three age groups: age at diagnosis 70–74, 75–79, ≥80 years. Extent of disease was grouped into four categories based on the information reported to the cancer registry: 1) localized; 2) local/regional spread (regional lymph nodes or adjacent tissues); 3) distant (distant metastases); 4) unknown extent.

The proportion of cases diagnosed at the age of 70 years and older among all adult cases varied from 30% for breast cancer to 56% for prostate cancer. The proportion of men decreased with increasing age. All quality indicators showed worse results in the oldest age group. The distribution of the extent of disease varied across cancer sites, but the proportion of cases with an unknown stage increased with age for all sites.

One-year and 5-year relative survival is shown for all patients aged ≥70 years as well as for three age-groups. The highest 1-year and 5-year RSRs were seen for prostate cancer (88% and 70%, respectively) and the lowest for lung cancer (23% and 6%, respectively). Relative survival generally decreased along with increasing age. Five-year RSR was higher among women for all sites, although the difference was not statistically signifi cant.

The RSRs for patients aged ≥70 years at diagnosis were lower than previously published estimates for middle-aged patients in Estonia. At the same time, these RSRs were also lower than those published for US patients aged ≥75 years during 1996–2000, particularly for cancers of the colon, breast, prostate, kidney and urinary bladder. The lower proportion of cases with microscopical verification and the higher proportion of cases with an unknown stage among the elderly suggest that these patients have been less thoroughly investigated compared with younger patients. More advanced stage at diagnosis is one of the possible explanations behind lower survival, but the role of comorbid conditions, treatment compliance and socioeconomic factors remains to be investigated.