Rural-urban comparisons of diabetes prevalence were made in te Polynesian population of Western Samoa. The prevalence of diabetes in the urban population was almost three times that in the rural (10.1% versus 3.6%). While the urban male and female subjects were significantly more obese than their rural counterparts, the difference in prevalence rate could not be wholly explained on the basis. Diabetes prevalence was still approximately double in urban subjects when we compared the rural and urban populations after removing the differences in obesity and age. The results suggest that, apart from age and obesity, other factors, e.g., differences in diet, physical activity, or stress (or a combination of these), may participate in the rural to urban difference in diabetes prevalence.

Between 1950 and 1978 754 patients underwent operation by one of the authors for carcinoma of the colon. Follow-up data were available on 99 per cent. Tumour stage distribution did not differ significantly with increasing duration of symptoms. The proportion of curative to palliative operative procedures was unrelated to symptom duration. Cancer specific survival for the entire patient series was worse when symptoms had been present for less than 3 months compared with 3-6 months, 6-12 months or 12 months or more (P less than 0.001, P less than 0.02 and P less than 0.04, respectively). Cancer specific survival after curative resection was also worse in patients with a symptom duration of less than 3 months compared with 3-6 months or 12 months or more (P less than 0.02 and P less than 0.03, respectively). These results show that colon cancer patients in whom the diagnosis is made and operation performed after a short symptomatic period do not have less advanced tumours nor better survival prospects.

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A comparison of the implantation rates following in vitro fertilization (IVF) and embryo transfer (ET) for four major groups indicates differences in the implantation rates as well as in the incidence of multiple implantation. By assuming that the probability of implantation is the product of two variables, uterine receptivity (U) and embryo viability (E), estimates for U and E are derived for each of the four IVF groups using maximum likelihood methods. The UE model is tested using chi-squared goodness-of-fit methods for predicted implantation rates versus observed. The possibility that differences in U values between groups are due to different ovarian stimulation protocols is discussed, as is the value of the UE model in highlighting differences between IVF groups and its importance in predicting multiple pregnancy rates.

Recurrence data from a series of 1,315 colorectal cancer patients managed by one surgeon with potentially curative resection are presented. Complete follow-up information was available on 1,287 (98%) patients. At the time of the last recurrences, 164 and 232 months for rectal and colonic tumours respectively, the long-time recurrence rate was significantly (P = 0.001) higher for rectal tumours (42%) than for colonic (33%). Although local recurrences tended to be more common in rectal than in colonic tumours (18% compared to 15%), only those in contiguity with the operative area were significantly (P less than 0.005) more common in rectal tumours. Systemic recurrences were also significantly (P less than 0.025) commoner for rectal tumours. The greater recurrence rates in rectal tumours were associated with significantly (P less than 0.001) higher incidence of stage C tumours shorter recurrence-free survival in rectal stage C tumours (P = 0.001) and higher incidence of pulmonary metastases (P less than 0.001).