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M C Pike

Publications and source records attributed to M C Pike.

At least 181 records · Page 10Linked to original sources
PubMed1988

Re-evaluating the role of progestogen therapy after the menopause.

An estrogen-progestogen regimen of hormone replacement therapy has become widely used in recent years, primarily as a means to protect the endometrium from the carcinogenic effects of unopposed estrogen therapy (ERT). In this article, we evaluate the probable effects of this regimen on mortality from endometrial cancer as well as mortality from other chronic diseases. We conclude from this analysis that ERT is to be preferred to combination therapy for postmenopausal women without a uterus, primarily because it is predicted that ERT confers a significantly greater benefit on heart disease risk. In women with a uterus, if progestogens are to be prescribed, they should be given in the lowest possible dose needed to achieve the desired histologic changes in the endometrium, since the predicted loss in heart disease benefit from adding the progestogen is substantial.

Breast Neoplasms↗
PubMed1987

Age-related factors in cancers of the breast, ovary, and endometrium.

The most central epidemiological feature of cancers of the breast, ovary and endometrium is the enormous protective effect of menopause. Simple mathematical "models" of the age-incidence of these tumours suggests that their incidence by age 70 would be between 4 and 8-fold increased if women continued to menstruate into old age. Using the notion of "effective cell-cycle time" to explain this phenomenon, different "models" are constructed for each of these three tumour sites and shown to provide an excellent description of most of the known epidemiology of each of the cancers, and to provide a basis for predicting the long-term effects of various factors on the risk of these diseases. In particular, the model suggests that 5 years of combination-type oral contraceptive use will approximately halve the lifelong risk of both ovarian cancer and endometrial cancer.

Adult↗
PubMed1987

Fitting models of carcinogenesis to a case-control study of breast cancer.

Data from a case-control study of breast cancer in 441 cases and matched controls aged less than or equal to 38 in Los Angeles is fitted to two models of carcinogenesis: the two-stage model of Moolgavkar and Knudson; and a multistage adaptation of the log/log model proposed by Pike et al. In the two-stage model, risk factors (here age at menarche, age at first pregnancy, abortion, regularity of cycling, benign breast disease, and use of oral contraceptives (OCs] are postulated to act either by increasing the rate of mutation of normal to intermediate or of intermediate to malignant stage cells, or by increasing the proliferation rates of such cells. In the multistage model, it is postulated that all transition rates are equally determined by the rate of cell turnover, which is in turn influenced by risk factors. In both models, positive family history is modelled in two ways: (1) all cells may have started in an intermediate stage at birth, with probability depending on the number and degree of affected family members; or (2) as an event rate modifier in the same way as other covariates. With only menarche or menarche and family history included, the multistage and two-stage models both produced likelihoods very similar to those from a simple logistic model, though both fit better than the logistic model as more covariates were added to the model. The two stage models offer greater flexibility in modelling the time at which each factor is most effective. We found irregular menstrual cycling to reduce the rate of proliferation of normal cells or their mutation rate to intermediate cells by 50% (p less than 0.025) and use of OCs to increase these rates by 3.25 fold (p less than 0.01). Having completed a pregnancy of more than 26 weeks gestation appeared to reduce the rate of intermediate cell proliferation by 5% (p less than 0.05) relative to a baseline rate of 14% per year. Benign breast disease was associated with a 1.60 fold increased rate of the second mutation (p less than 0.025). In all models, family history was by far the strongest risk factor (RR = 4.44 from the logistic model, p less than 0.0001). Covariates showed similar effects in the multistage model, though their magnitudes were slightly different.

Adult↗
PubMed1987

Sex hormone binding globulin and risk factors for breast cancer in a population of normal women who had never used exogenous sex hormones.

Sex hormone binding globulin (SHBG) concentrations were measured by immunoradiometric assay in serum samples from 1,221 healthy female volunteers aged 34-79 who had never used oral contraceptives or hormone replacement therapy, had no history of thyroid disease or cancer, and had not used any drugs known to influence SHBG in the 14 days preceding blood sampling. There were 616 premenopausal and 605 naturally postmenopausal women. In both premenopausal and postmenopausal women, SHBG decreased with increasing weight (Quetelt's Index) and was lower in single nulliparous women than in married nulliparous women or parous women. In premenopausal women, SHBG was higher in women with late menarche, was higher in smokers than in non-smokers, and was higher in blood samples taken during the first 12 days of the luteal phase than during the rest of the menstrual cycle. In postmenopausal women, SHBG increased with years since the menopause. The possible biological importance of these findings is discussed with particular reference to risk factors for breast cancer.

Adult↗
PubMed1987

Thyroid cancer among young women related to prior thyroid disease and pregnancy history.

We conducted an epidemiologic case-control study of thyroid cancer in women aged 40 and under to test the hypothesis that endogenous hormones may relate to the development of this disease, since the only known cause of thyroid cancer, ionizing radiation, does not account for the striking female over male excess. When compared to neighbour controls women with thyroid cancer more often had a history of benign hyperplastic thyroid disease (Relative Risk (RR) = 14.5; P less than 0.01) and more often had ever been pregnant (RR = 2.1; P = 0.04). Both these findings were consistent with findings of previous studies. After eliminating women with a history of hyperplastic thyroid disease from the analysis we found a strong association with miscarriage as the outcome of the first pregnancy (RR = 11.5; P less than 0.01), and we suspect that this factor may be another indicator of thyroid abnormality. An independent and increasing risk was observed with an increase in the total number of pregnancies after excluding women with prior thyroid disease and those whose first pregnancy ended in a miscarriage. The RR for 4 or more pregnancies was 6.3 (P = 0.03). Prior exposure to radiation therapy was not an important factor in our study of young women; this suggests that the emphasis in future studies of thyroid cancer must shift to study other types of risk factors.

Abortion, Spontaneous↗
PubMed1987

Trends in breast cancer mortality and diet in England and Wales from 1911 to 1980.

A paper in a previous volume of this journal (Ingram, DM, Nutr Cancer 3, 75-80, 1981) reported that at the beginning of World War II there was a marked decrease in breast cancer mortality in England and Wales that coincided with a marked reduction in the consumption of sugar, meat, and fat, and a marked increase in the consumption of cereals and vegetables. Reexamination of the mortality data described in that paper shows that the apparent sudden decrease in breast cancer mortality at the beginning of World War II is an artefact caused by a change in the method of selecting the cause of death from jointly stated causes, which was introduced in 1940. After adjusting for this change, trends in age-specific mortality rates are described. Breast cancer mortality rates were greater in 1980 than in 1911 in the age group of 35-84 years, but this overall increase was interrupted by a period of decreasing mortality between the 1930s and the 1950s in the age group of 50-69 years. It is possible that some of this decrease was due to dietary changes; however, the evidence is poor and other factors that affect incidence and survival must be considered.

Adult↗
PubMed1986

Risk factors for uterine fibroids: reduced risk associated with oral contraceptives.

Risk factors for pathologically confirmed uterine leiomyomas (fibroids) were investigated using data from the Oxford Family Planning Association study, a long term follow up study of women using various methods of contraception. For each of 535 women who had had a fibroid an individual control was selected who matched the patient on age, date of entry into the cohort, and family planning clinic at recruitment and who was alive (and still being followed up) at the date the patient underwent surgery for fibroids. Case-control analysis showed that reproductive experiences were closely linked to development of fibroids. Risk of fibroids decreased consistently with increasing number of term pregnancies; women with five term pregnancies had only a quarter of the risk of women who had had none. Risk also decreased consistently with increasing duration of oral contraceptive use; the risk of fibroids was reduced by some 31% in women who had used oral contraceptives for 10 years. Risk was strongly related to weight: women who weighed under 55 kg had a particularly low risk, and overall the risk rose roughly 21% for each 10 kg increase. Cigarette smoking was associated with a decreased risk of fibroids; smokers of 20 cigarettes a day had a risk roughly two thirds that of non-smokers. These risk factors have all previously been identified as risk factors for endometrial cancer; this strongly suggests that the underlying risk factor is "unopposed" oestrogen.

Adult↗
PubMed1986

Effect of age at orchidopexy on risk of testicular cancer.

69 (9.5%) of 724 patients with testicular cancer first seen at the Royal Marsden Hospital over the 10-year period 1975 to 1984 had a history of cryptorchidism. 11 patients had an uncorrected undescended testis when their testicular cancer was diagnosed, and 58 had had an orchidopexy or an orchidectomy for undescended testis. There are no general population data with which to compare the 15.9% (11/69) of testicular cancer patients with uncorrected cryptorchidism. However, the distribution of age at orchidopexy (or orchidectomy) of the 58 patients treated for undescended testis was almost identical to that expected on the basis of national rates. The age at treatment of undescended testis appears to have no effect on the risk of testicular cancer.

Adolescent↗
PubMed1986

Undescended testis: the effect of treatment on subsequent risk of subfertility and malignancy.

The literature was reviewed for information on the long-term effects of cryptorchidism on fertility and cancer incidence. In unilateral cryptorchidism, treatment policies of orchidopexy alone, or of human chorionic gonadotrophin (hCG) therapy followed, if necessary, by orchidopexy, have resulted in similar levels of reduced fertility (15% azoospermia, and an additional 30% oligospermia, ie, sperm count less than 20 X 10(6)/mL). Very similar results were observed in unilateral cryptorchid men who had had no treatment (and were still cryptorchid at semen examination). In contrast, no untreated bilaterally cryptorchid men have normal fertility (sperm count greater than 20 X 10(6)/mL), whereas of those treated, a quarter have normal fertility. In some series, as many as half of the bilateral cryptorchid testes descended following hormonal treatment; a finding that could be attributed, at least in part, to the frequent difficulty in deciding on clinical examination, whether these testes are truly cryptorchid. There is little evidence that operation early rather than late within the age range of 4 to 14 years has any effect on subsequent fertility. Histologic studies suggest that orchidopexy should be carried out before age 2, but there are almost no follow-up data with which to evaluate the results of early operation. Since there is evidence that orchidopexy may result in testicular atrophy in a small proportion of cases, a trial of luteinizing hormone-releasing hormone (LHRH) may be advisable. There is little information available concerning the effect of age at orchidopexy on the subsequent risk of testicular cancer. Testes that cannot be brought into the scrotum should be excised.

Age Factors↗