Reduction of socioeconomic inequality in cancer incidence in the South of the Netherlands during 1996-2008
Background: Cancer incidence varies according to socioeconomic status (SES) and time trends. SES category may thus point to differential effects of lifestyle changes but early detection may also affect this. Patients and methods: We studied patients diagnosed in 1996-2008 and registered in the South Netherlands Cancer registry. Incidence rates and estimated annual percentage changes were calculated according to SES category, age group (25-44, 45-64 and ≥65) and sex. Results: People with a low SES exhibited elevated incidence rates of cancer of the head and neck, upper airways (both sexes), gastro-intestinal tract, squamous cell skin cancer, breast (≥65) and all female genital, bladder, kidney and mature B-cells (all in females only), whereas prostate cancer, basal cell skin cancer (BCC) and melanoma (both except in older females) were most common among those with a high SES. Due to the greater increase in prostate cancer and melanoma in high SES males and the larger reduction of lung cancer in low SES males, incidence of all cancers combined became more elevated among males of ≥45 years with a high and intermediate SES, and approached rates for low SES men aged 45-64. In spite of more marked increases in the incidence of colon, rectal and lung cancer in high SES women, the incidence of all cancers combined remained highest for low SES women of ≥45 years. However, at age 25-44 years, the highest incidence of cancer of the breast and melanoma was observed among high SES females. During 1996-2008 inequalities increased unfavourably among higher SES people for prostate cancer, BCC (except in older women) and melanoma (at middle age), while decreasing favourably among low SES people for cancers of the oesophagus, stomach, pancreas and kidney (both in females only), breast (≥65 years), corpus uteri and ovary. Conclusions: Although those with a low SES exhibited the highest incidence rates of the most common cancers, higher risks were observed among those with high SES for melanoma and BCC (both except older females) and for prostate and breast (young females) cancer. Altogether this might also have contributed to the recent higher cancer awareness in Dutch society which is usually promoted more by patients of high SES and those who know or surround them.