Trends in colorectal cancer incidence and mortality in New South Wales, 1973-1992

OBJECTIVE

To assess changes in incidence and mortality rates of colorectal cancer in different age groups in New South Wales (NSW) between 1973 and 1992.

DESIGN

Descriptive analysis of data on incidence and mortality from the population-based NSW Central Cancer Registry and on colorectal cancer diagnostic tests from the Health Insurance Commission.

MAIN OUTCOME MEASURES

Age-standardised incidence and mortality rates for colon and rectal cancer (defined by codes 153 and 154 in the International classification of diseases, 9th revision) by sex and age group (15-44, 45-59, 60-74 or > or = 75 years) and incidence by cancer spread at diagnosis; age-standardised rates for faecal occult blood tests, sigmoidoscopy and colonoscopy.

RESULTS

From 1973 to 1992, colorectal cancer incidence increased significantly in NSW by an average of 2.0% per year in males (95% confidence interval [CI], 1.8 to 2.3) and 0.9% in females (95% CI, 0.7 to 1.1). Mortality rates remained nearly constant in males, but fell significantly in females by an average of -1.0% per year (95% CI, -1.3 to -0.7). In the youngest age group (15-44 years) both incidence and mortality rates fell significantly, while rates were stable or rose in older age groups, except for a significant fall in mortality in women aged > or = 75 years. Use of colonoscopy (an early detection method) increased, but a corresponding shift to detection of earlier-stage cancers was not seen.

CONCLUSIONS

A reduction in risk factors and better treatment leading to longer survival may have contributed to the falls in incidence in younger people and in mortality in females.

The occurrence of cancer in a cohort of New South Wales coal miners

To describe the incidence of cancer in coal miners in New South Wales (NSW) between 1973 and 1992, an inception cohort of all male coal industry employees who entered the industry between 1 January 1973 and 31 December 1992 was constructed from the medical examination records of the Joint Coal Board. This cohort was matched with the NSW State Cancer Registry to determine the occurrence and type of cancer. In the cohort of 23,630 men, 297 developed 301 primary cancers in the 20-year period of observation. The standardised incidence ratio (SIR) for all cancers was 0.82. Stomach cancer has been reported to be common in coal miners but the SIR for stomach cancer was not higher than average in this cohort. A cluster of non-Hodgkin's lymphoma has been reported in a NSW coal mine but an increased risk of this cancer was not evident in the industry as a whole. Similarly a cluster of cases of brain tumour has been reported. In this cohort, the SIR for brain tumour was 1.05 (95 per cent confidence interval (CI) 0.57 to 1.76) and a risk for brain tumour remains unconfirmed. The SIR for malignant melanoma was 1.13 (CI 0.90 to 1.39) together and 2.02 (CI 1.31 to 2.98) for those workers who started in an open-cut mine. Overall, there does not appear to be a general risk of cancer in the NSW coal industry. Open-cut miners have an increased risk of malignant melanoma, which may be related to their exposure to the sun at work.

Changes in cancer incidence and mortality in New South Wales

OBJECTIVE

To assess changes in cancer incidence and mortality in New South Wales (NSW) between 1973-1977 and 1988-1992.

DESIGN

Descriptive analysis of statutory cancer notifications to the NSW Central Cancer Registry.

OUTCOME MEASURES

Age-standardised incidence and mortality rates calculated with the "world" standard population.

RESULTS

Overall cancer incidence rose markedly, from 251 to 318 per 100,000 in men and from 202 to 241 per 100,000 in women. The rise was greatest in the 60-and-over age group. Cancer mortality fell marginally in men (from 166 to 162 per 100,000) and did not change in women (100 per 100,000 in both periods). It fell in the under-60 age group, and remained stable or rose in older people. Prostate and breast cancers and melanoma of the skin accounted for about half the increase in incidence. Both incidence and mortality increased significantly (P < 0.01) for melanoma and non-Hodgkin's lymphomas in men and lung cancer in women, and fell substantially for stomach cancer in both sexes, lung cancer in men and cervical cancer in women. Despite increasing incidence, mortality, also fell for testicular cancer in men and rectal cancer in women and for leukaemias in children.

CONCLUSIONS

The major factor causing the increased incidence of overall cancer was earlier detection. Altered exposure to risk factors could be identified for only a minority of the changes.

Mortality in the New South Wales coal industry, 1973-1992

OBJECTIVE

To study the mortality of coalminers in New South Wales (NSW) between 1973 and 1992.

DESIGN AND PARTICIPANTS

An inception cohort of all male coal industry employees who entered the industry between 1 January 1973 and 31 December 1992 was constructed from the records of Joint Coal Board medical examinations. This cohort was matched with the NSW Death Register to determine the number and causes of deaths in cohort members.

RESULTS

The cohort consisted of 23,630 men; 491 died during the study period. The standardised mortality ratio (SMR) for all causes of death was 0.76; that is, after age correction, coalminers have a 24% lower mortality than the general NSW population. Deaths from cancer were lower than expected, and there was a 27% lower mortality from respiratory disease. However, a substantial excess of non-motor-vehicle accidents (SMR, 1.60) was found. Most of these deaths can be attributed to occupation, and some to specific incidents. These excess death rates are confined to underground miners; open cut miners have a substantially lower rate than the general population.

CONCLUSIONS

A "healthy worker" effect may explain the lower overall mortality. Although "black lung" is no longer a problem, accidents are still common in underground coalmining. The major expansion of open cut mining in recent years has improved the situation.

An analysis of a melanoma epidemic

Between 1986 and 1988 the annual incidence of invasive melanoma in the Hunter area of New South Wales, Australia, almost doubled to 52.5 per 100,000 in men and 42.9 per 100,000 in women. These rates have been maintained and are similar to those reported for 1987 in Queensland, Australia, which are the highest in the world. Most of the increase in incidence was in melanomas less than 1.50 mm in thickness, and adults of both sexes and all ages were affected. Thicker melanomas also increased in incidence but only in adults 45 years and older, and mainly in men. An analysis of health insurance data on treatment of skin lesions and data from a histopathology laboratory suggested that diagnosis and treatment of skin lesions generally in the Hunter area had increased almost 2-fold over this period. Advancement of the time of diagnosis and a real increase in incidence were likely explanations for some of the observed trends. Increasing diagnosis of a non-metastasising form of thin melanoma, consequent upon increasing removal of pigmented skin lesions by medical practitioners, may also explain some of the observed increase in the incidence of the disease. This possibility has important implications for proposed population screening programs, and methods are needed to distinguish such lesions, if they exist, from potentially fatal melanoma.

Cancer incidence in migrants to New South Wales from England, Wales, Scotland and Ireland

Cancer incidence in migrants to New South Wales (NSW) from individual countries within the British Isles has been compared with that in the Australian-born population using data from the NSW Central Cancer Registry for the period 1972-84. Indirectly age-standardised incidence ratios (SIR) showed that, for cancer at all sites combined, Scottish migrants had a significantly higher, and English migrants a lower, incidence than the native-born Australians. Melanoma of skin was less common in migrants from all four countries while lung cancer was more common. In all except the Irish migrants, stomach cancer was more frequent than in the Australian-born. Raised SIRs for bladder cancer were found in men from all the countries and for breast cancer in all except the Irish women but only in the English migrants were these ratios significant. English migrants differed from those from Wales, Scotland and Ireland in that, compared with the Australian-born, they had significantly lower SIRs for cancer of the colon (both sexes), head and neck, larynx and prostate (men), gallbladder and kidney (women), and a higher SIR for ovarian cancer. Bone cancer was relatively more common in men born in Wales. 'Other genital' cancers (penis and scrotum; vulva and vagina) tended to be more frequent in migrants from each country than in the Australian-born.

Geographical distribution of cancers of the kidney and urinary tract and analgesic nephropathy in Australia and New Zealand

Age-standardised incidence rates for cancers of the renal parenchyma, renal pelvis and bladder and for end-stage renal failure due to analgesic nephropathy for the years 1982-83 were compared between the Australian states and New Zealand, and within New South Wales (NSW), to determine whether these rates paralleled the previous prevalence of consumption of phenacetin-containing analgesics. Whereas little variation was seen within Australasia in respect of the incidence of cancer of the renal parenchyma and bladder, both cancer of the renal pelvis and end-stage renal failure due to analgesic nephropathy had higher incidence rates amongst women in NSW and Queensland than in the other states or New Zealand. Within NSW, the average annual incidence rates during 1973-82 for renal pelvic cancer in the Hunter region of 1.3 (m) and 1.6 (f) per 100,000 were the highest in the state. These high incidence rates coincided with areas known to have had a high prevalence of consumption of compound analgesics containing phenacetin. In an international comparison with populations which had published incidence rates for each of the periods 1973-77 and 1978-82, the rate for cancer of the renal pelvis in women was highest in both time periods in NSW and had increased absolutely at a faster rate.

Cancer incidence in migrants to New South Wales

Cancer incidence in migrants to New South Wales (NSW) from the British Isles, north-central, eastern and southern Europe, the Middle East and Asia has been compared with that in Australian-born residents using data from the NSW Central Cancer Registry for 1972-84. Indirectly standardized incidence ratios (SIRs) were low in migrants from all 6 regions for melanoma of skin and cancers of lip and, except in men from eastern Europe, colon. Oesophageal, rectal and prostatic cancers also tended to be relatively less common. Cancers which were more common than in the Australian-born were those of the stomach and, for men, bladder (except in the Asian-born). Migrants from different regions showed variations from the cancer pattern of the Australian-born population which, for the most part, were predictable from the known incidence of cancer in the countries within the region of origin. Exceptions were the high relative incidence of nasopharyngeal cancer in migrants from southern Europe and bladder cancer in men from all regions other than Asia.

Cancer incidence in New Zealand born residents of New South Wales

Cancer incidence in New Zealand born residents of New South Wales (NSW) has been compared with that in the Australian born population using data from the NSW Central Cancer Registry for the period 1972-84. Indirectly age-standardised incidence ratios (SIR) showed that New Zealand born women living in NSW had higher rates of cancer at all sites combined (SIR = 112) and a significant excess of colorectal cancer (SIR = 126). Although overall cancer rates were similar in men born in New Zealand to those in the Australian born men, the New Zealanders had a significantly higher risk of colorectal (SIR = 124) and testicular cancer (SIR = 227), cancers which are more common in New Zealand than in Australia. While the SIRs for lung cancer in men and melanoma of skin in both sexes were low, no cancer was significantly less common in New Zealand born residents of NSW than in the Australian born.

Cancer incidence in European migrants to New South Wales

The incidence of cancer in migrants to New South Wales (NSW) from Italy, Greece, Yugoslavia, Germany, the Netherlands, Poland and USSR has been compared with that in the Australian-born population using data from the NSW Central Cancer Registry for 1972-84. The indirectly age-standardized incidence ratios (SIR) in all seven countries were low for melanoma of skin and high for gastric cancer. Cancers of the colon, oesophagus and lip also tended to have low SIRs. Migrants from Italy, Greece and Yugoslavia had significantly less cancer at all sites than the native-born Australians mainly due to low SIRs for cancers of colon, lung (except Yugoslavian-born men), prostate and, in men, 'head and neck' (excluding nasopharynx). Cancers of breast and testis were relatively less common in migrants from Italy and Yugoslavia. SIRs were high for cancers of bladder (in Italian-born men), liver (in Greek- and Yugoslavian-born men) and nasopharynx (in Greek-born men and Italian-born men and women). Amongst migrants from the four more northerly European countries, ovarian cancer was relatively more common in women from Germany and Poland as was bladder cancer in men, but not women, from Germany and the Netherlands. Cancers which had significantly increased SIRs in one migrant group only were lung (Dutch-born men), cervix uteri and body of uterus (German-born women), gallbladder and bile ducts (Polish-born women), thyroid (Italian-born women), connective and other soft tissue (Russian-born men) and brain (Greek-born men and women computed together). Lymphomas were relatively less common in men born in Yugoslavia.

Trends in invasive cancer of the cervix uteri in New South Wales, 1973-1982

Data from the New South Wales (NSW) Central Cancer Registry comprising all new cases of, and deaths from, invasive cancer of the cervix uteri registered in persons aged 15 years and over for the 10-year period 1973 to 1982 were examined using log-linear regression to determine whether incidence and mortality had been changing in NSW. Allowing for the estimated fraction of women who had undergone hysterectomy, this cancer had decreased significantly in incidence (-1.3% per year) as well as mortality (-3.6%). There were no significant trends in relation to age at diagnosis, stage at diagnosis or histological type. Overall, younger age at diagnosis was associated with an earlier stage at presentation and there was no evidence for a trend towards more severe disease in young women during the 10-year period. No evidence was found for an increasing incidence of adenocarcinoma. By 1982 the age-standardized incidence rate was 10.4 per 100,000 (12.5 per 100,000 after adjustment for the hysterectomy fraction). Cancer of the cervix uteri was more common in Inner and Western Sydney and less common in the Northern Metropolitan region of Sydney and rural New South Wales.

The changing incidence of cancer in adults in New South Wales

Data from the New South Wales (NSW) Central Cancer Registry comprising all new cases of cancer registered in persons aged 15 years and over for the 10-year period 1973 to 1982 were examined using log-linear regression to determine whether the incidence of cancer had been changing in NSW. Allowing for the altered age and sex structure of the population over this period, the annual incidence rate for all sites combined increased significantly by 1.7% in men and 1.0% in women. Cancers which had increased at a rate significantly greater than that for all sites combined were those of unknown primary site (8.7% per year), lung (in women only, 5.6%), kidney (4.5%), bladder (2.7%) and rectum (2.6%) and lymphomas (2.6%). Other cancers which showed a significantly increased incidence rate per se were testis (3.5%), larynx (3.2%), prostate (2.1%), colon (1.7%), brain (1.6%), leukaemias (1.3%) and lung (in men only, 0.7%). Cancers which had decreased significantly in incidence were those of oesophagus (-2.2%), cervix uteri (-2.0%) and stomach (-1.4%). No significant change in incidence over the 10 years had occurred for cancers of the corpus uteri, breast, ovary or pancreas.