Susan Kune

Case‐control study of dietary etiological factors: The Melbourne colorectal cancer study

As part of a large-scale investigation of colorectal cancer (CRC) incidence, etiology, and survival, a case-control study was conducted to identify dietary factors associated with the risk of CRC. The study compared 715 cases with 727 age- and sex-matched community controls. A quantitative diet history, assessed to be the most representative of the previous 20 years, was obtained from each subject and analyzed for both food groups and nutrients. The combination of a high-fiber and high-vegetable intake was found to be protective against large bowel cancer. Cruciferous vegetable intake was also found, although with less certainty, to be protective. Dietary vitamin C was protective for estimated intakes greater than 230 mg/day. Dietary Beta-carotene had no separate association with the risk of CRC. Beef intake was a risk factor in males but not in females. Fat intake was a risk factor for both males and females. A low intake of milk drinks was a risk for both males and females. A high intake of pork and fish was protective. The use of vitamin supplements was highly protective. A risk score, which was calculated as the number of risk factors an individual has in his or her diet, showed an increasing monotonic relationship with risk of CRC. The effects of the dietary variables were similar for colon and rectal cancer and, with the exception of beef, were similar for males and females.

Case-control study of alcoholic beverages as etiological factors: The Melbourne colorectal cancer study

As part of a large-scale investigation of colorectal cancer incidence, etiology, and survival, a case-control study was conducted to identify whether diet and alcohol, among other variables, were associated with the risk of colorectal cancer. This study compared 715 cases with 727 age- and sex-matched community controls. Findings from the dietary data are presented in the previous paper (Nutr Cancer 9, 21-42, 1987). The total life intake of specific alcoholic beverages was obtained from each subject. Data were classified by consumption of beer, wine, spirits, and alcohol. There was little evidence of an association of any of the alcohol variables with the risk of colon cancer. However, beer was found to be a risk factor for rectal cancer. This effect was more marked in males than in females, but the relative risks for females were consistent with those for males. Relative risk estimates changed only slightly when adjusted for the other alcohol variables and for the variables in the diet model; this suggests that the beer effect is separate from that of other alcohol variables and also from dietary variables. The age differences among beer consumers were found to be associated with cancer risk. Consumption of spirits was associated with a low risk for male rectal cancer. The risk of rectal cancer appeared to depend on beer drinking patterns in the previous 15-20 years.

The Role of Heredity in the Etiology of Large Bowel Cancer: Data from the Melbourne Colorectal Cancer Study

Family history data of colorectal cancer, heart disease, and stroke were obtained on near relatives (parents, siblings, and children) in 702 colorectal cancer cases and 710 age-/sex-matched community controls as part of a large, comprehensive, population-based epidemiological and clinicopathological study of colorectal cancer conducted in Melbourne (the Melbourne Colorectal Cancer Study). There was a statistically significant higher family history rate of colorectal cancer in cases than in controls (relative risk=2.13; 95% confidence interval=1.53–2.96;p< 0.001). This family history effect was more pronounced for colon cancer than for rectal cancer and there was an earlier age of detection of colorectal cancer in those with a family history of this cancer when compared with those without such a history. Dietary risk factors for colorectal cancer, which were previously described in the Melbourne study, were separate and independent from the family history effects. It is concluded that a family history of colorectal cancer is an important indication to screen individuals for this cancer, and also that while heredity has a definite role in the etiology of colorectal cancer, this hereditary effect is either likely to be small, or else likely to be important in only a proportion (perhaps 20%) of cases.RésuméLes antécédents de cancers familiaux colorectaux, maladie cardiaque, et accidents vasculaires cérébraux ont été recueillis des proches parents (parents, fratrie, et enfants) chez 702 patients ayant présenté un cancer colorectal et chez 710 sujets témoins comparables en ce qui concerne lâge et le sexe, dans une étude à grande échelle, épidémiologique, et anatomoclinique sur le cancer colorectal, menée à Melbourne, Australie (Melbourne Colorectal Cancer Study). Il y avait plus dantécédents familiaux de cancer colorectal chez ceux qui avaient un cancer que chez les témoins (risque relatif=2.13; intervalle de confiance à 95%=1.53–2.96;p<0.001). Ceci était plus net pour les patients ayant un cancer colique que pour ceux qui avaient un cancer rectal. Le cancer était détecté plus tôt chez les patients ayant des antécédents familiaux de cancer que chez ceux qui nen avaient pas. Les risques alimentaires du cancer colorectal déjà décrits nétaient pas liés aux antécédents familiaux. Les antécédents familiaux de cancer colorectal sont un facteur important dans le dépistage de ces cancers. Lhérédité joue un rôle important dans lédologie du cancer colorectal chez 20% des patients.ResumenLa predisposición hereditaria y la dieta representan las 2 principales hipótesis sobre etiología del cáncer colorrectal. La información contenida en este artículo proviene de un amplio estudio comprensivo, clinicopatológico, y epidemiológico sobre la incidencia, etiología, y sobrevida (el Estudio de Melbourne sobre Cáncer Colorrectal), y los datos de historia familiar provienen de casos controlados del estudio. Los datos de historia familiar de cáncer colorrectal, enfermedad cardiaca, y accidente cerebrovascular fueron obtenidos en familiares cercanos (padres, hermanos, e hijos) de 702 pacientes con cáncer colorrectal y de 710 personas control de similar edad y sexo, en la misma comunidad de Melbourne. Se encontró una estadísticamente significativa mayor tasa de historia familiar de cáncer colorrectal en los pacientes que en los controles (riesgo relativo=2.13; 95%, intervalo confidencial=1.53–2.96;p<0.001). Tal efecto de historia familiar apareció más pronunciado en el cáncer del colon que en el cáncer del recto, y se observó una edad de detección más temprana del cáncer colorrectal en los pacientes con historia familiar de este tipo de cáncer, en comparación con aquellos sin la historia familiar. Los factores dietéticos en el cáncer colorrectal, los cuales fueron previamente descritos en el estudio de Melbourne, aparecieron aislados e independientes de los efectos de la historia familiar. Se présenta la conclusión de que la historia familiar de cáncer colorrectal es una importante indicación para el tamizaje individual, y también de que si bien es cierto que la herencia posee una influencia definitiva en la etiología del cáncer colorrectal, este efecto hereditario aparentemente es menor o sólo llegar a ser de importancia en apenas una parte (tal vez 20%) de los casos.

The role of chronic constipation, diarrhea, and laxative use in the etiology of large-bowel cancer: Data from the Melbourne Colorectal Cancer Study

Life-long bowel habits of 685 colorectal cancer cases and 723 age/sex frequency matched community controls were investigated as one part of a large, comprehensive, population-based study of colorectal cancer incidence, etiology, and survival, The Melbourne Colorectal Cancer Study. Self-reported chronic constipation was statistically significantly more common in cases than in controls (P=.05). Three or more bowel actions per day were reported by more cases than controls but the total number of respondents in this subset consisted of only ten cases and two controls. Otherwise, the frequency and consistency of bowel motions was similarly distributed among cases and controls. Constipation disappeared as a significant risk when simultaneously adjusted for previously determined dietary risk factors, indicating that it is the diet and not the constipation that is associated with the risk of large-bowel cancer. Additionally, a highly statistically significant association (P=.02) was found with the risk of colorectal cancer in those who reported constipation and also had a high fat intake, a finding consistent with current hypotheses of colorectal carcinogenesis. It is concluded that chronic constipation, diarrhea, and the frequency and consistency of bowel motions, as well as laxative use, are unlikely to be etiologic factors in the development of colorectal cancer. Self-reported chronic constipation is a marginally significant indicator of excess risk of large-bowel cancer and may be used as one of the indices in the screening of individuals for this cancer.

The melbourne colorectal cancer study

The characteristics of 702 colorectal cancer patients are described in relation to the presence or absence of a family history of colorectal cancer in near relatives. No statistically significant associations were found between those with a family history of colorectal cancer and age at detection, sex, country of birth, religion, number of cancers (single, synchronous, or metachronous), previously removed benign colorectal polyps, and adenomatous polyps found in the resection specimen. The family history rate of colorectal cancer for colon cancer cases was statistically significantly higher than for rectal cancer cases (χ12=3.8,P=0.5) and there was a gradient of decreasing risk from colon to rectum. The family history rate of colorectal cancer in parents of those who were less than 50 years old was twice that of those 50 or older (P=.07), consistent with the view that earlier age of onset is a characteristic of those with a family history of colorectal cancer. There was a statistically significantly higher family history rate of colorectal cancer in respondents who knew of the disease compared with those who did not (χ12=5.5,P<.05). It is unclear if this effect represents recall bias or self-selection bias. In contrast, the rates for a family history of heart disease and stroke were similar, irrespective of the respondents knowledge of their colorectal cancer status. Thus in the Melbourne study, the family history rate of colorectal cancer was higher in colon cancer than in rectal cancer, there was a decreasing gradient of risk from colon to rectum, and a tendency for earlier age of onset of colorectal cancer in those with a history of this cancer in a parent.

Observations on the reliability and validity of the design and diet history method in the Melbourne colorectal cancer study

The paper is a description of, and a practical guide to, the questions, problems, and pitfalls that can arise in the planning and execution of a large-scale epidemiological study of diet and disease; this study was an eight-year project in which diet histories were collected from over 2,000 people. Qualified dietitians obtained a quantitative diet history, which covered all foods eaten in Australia, and assessed as the most representative of the previous 20 years. Because over half of both cases and controls changed their diets in the previous 20 years, the period of recall nominated varied, but this was not a major bias. There was no effect of seasonality on recall. The average duration of the interview was one hour for both cases and controls. The response rate was 84% for cases and 94% for controls, suggesting that the time for interview of the diet history method is not a deterrent for a high response rate. In general, between-interviewer variation was small, although the intakes of total vegetables, cruciferous vegetables, and leafy green vegetables were the least repeatable. Between-interviewer differences were not found to affect the relative risks. Reproducibility of placing a dietary factor into a particular quintile of consumption was good for most foods, but it was lowest for cruciferous and leafy green vegetables. Interviewer bias regarding the dietary causes of colorectal cancer was not a major bias. Analysis of within-interviewer variation over time and analysis of recall bias were not major biases, as far as could be assessed in this study. Indirect validation of the nutritional data in the study (by comparison with other studies, by national per capita consumption, and by a comparison of energy intake with estimated energy requirements based on height, weight, and activity levels) suggested that the data are not an overestimate of intake. Cases and controls were both overestimating and underestimating their dietary intakes to a similar degree. For epidemiological studies of diet and disease, the quantitative diet history method as used here is recommended, particularly if the main objective of the study is to confirm hypotheses.

The nutritional causes of colorectal cancer: An introduction to the melbourne study

The Melbourne study has shown that dietary factors and alcohol are important in the cause and prevention of colorectal cancer (CRC). A high intake of fat and beef probably causes CRC, and a high intake of beer possibly causes rectal cancer. The beef and beer effects were both independent of other dietary variables, but further research is indicated to explore the mechanisms of their actions. Foods of plant origin protected against CRC, and the plant food hypothesis now replaces the dietary fiber hypothesis. Further study is needed on the interrelationships between various foods of plant origin. Vitamin supplements were protective, and again clarification is needed on the mechanism of action. In high-risk populations, nutritional risk and causal factors are likely to be difficult to find, whereas protective factors are likely to be found with greater ease. Further analysis of the Melbourne data will reveal the importance of diet in CRC causation, relative to the other hypothesized causal and protective factors.

The effect of family history of cancer, religion, parity and migrant status on survival in colorectal cancer

The association between 5-year survival and several risk factors was investigated in 705 histologically confirmed, new cases of colorectal adenocarcinoma as one aspect of a comprehensive population-based study of large bowel cancer incidence, aetiology and survival--the Melbourne Colorectal Cancer Study. 5-year survival was not influenced by the previously determined risk of a family history of colorectal cancer in near-relatives. Similarly, other previously determined risk factors of religion, number of children, age at birth of first child and migrant status did not influence survival.

Large bowel cancer after cholecystectomy

In a large, population-based case control study of colorectal cancer, 65 of 715 patients and 57 of 727 control subjects had a previous cholecystectomy (chi-square = 0.6, relative risk 1.18, 95 percent confidence interval 0.81 to 1.70, p = 0.45). There was no statistically significant association between previous cholecystectomy and the risk of colorectal cancer, colon cancer, right colon cancer, any of the subsites of colon cancer, rectal cancer, age, or sex. Although there is some evidence from other studies of an association between previous cholecystectomy and right colon cancer in women, this may have resulted from confounding symptoms. Based on the present evidence, we believe that previous cholecystectomy is unlikely to be a risk factor for colorectal cancer.

New Design to Examine Colorectal Cancer Cause and Survival

A brief description is given of a large and comprehensive population-based investigation of colorectal cancer with a new study design. The study design allows the simultaneous examination of the incid