Body weight, serum cholesterol, and stage of primary breast cancer

Circulating levels of PCSK9, ANGPTL3 and Lp(a) in stage III breast cancers

Background / synopsis

Cholesterol and lipids play an important role in sustaining tumor growth and metastasis in a large variety of cancers. ANGPTL3 and PCSK9 modify circulating cholesterol levels, thus availability of lipids to peripheral cells. Little is known on the role, if any, of circulating lipid-related factors such as PCSK9, ANGPTL3 and lipoprotein (a) in cancers.

Objective/purpose

To compare circulating levels of PCSK9, ANGPTL3, and Lp(a) in women with stage III breast cancer versus women with premalignant or benign breast lesions.

Methods

Twenty-three plasma samples from women diagnosed with a stage III breast cancer (ductal, lobular or mixed) were matched for age with twenty-three plasma samples from women bearing premalignant (stage 0, n = 9) or benign (n = 14) breast lesions. The lipid profile (Apo B, total cholesterol, HDL cholesterol and triglycerides levels) and Lp(a) were measured on a Roche Modular analytical platform, whereas LDL levels were calculated with the Friedewald formula. ANGPTL3 and PCSK9 plasma levels were quantitated by ELISA. All statistical analyses were performed using SAS software version 9.4.

Results

PCSK9 levels were significantly higher in women with stage III breast cancer compared to age-matched counterparts presenting a benign lesion (95.9 ± 27.1 ng/mL vs. 78.5 ± 19.3 ng/mL, p < 0.05, n = 14). Moreover, PCSK9 levels positively correlated with breast disease severity (benign, stage 0, stage III) (Rho = 0.34, p < 0.05, n = 46). In contrast, ANGPTL3 and Lp(a) plasma levels did not display any association with breast disease status and lipids did not correlate with disease severity.

Conclusion

In this small cohort of 46 women, PCSK9 levels tended to increase with the severity of the breast disease. Given that PCSK9 plays an important role in maintaining cholesterolemia, and a potential role in tumor evasion, present results warrant further investigation into a possible association between PCSK9 levels and breast cancer severity in larger cohorts of women.

Serum Lipid Profile and Its Relationship with Host Immunity in Carcinomas of the Breast and Uterine Cervix

Carcinomas of the uterine cervix and breast, which have a different etiopathogenesis, are the most common malignancies among Indian women. Between these two cancers a comparative study was undertaken in which serum lipids were assessed along with host immunity. Thirty randomly selected cases each of breast and cervical carcinoma, and 20 matched healthy control women were studied by means of standard procedures. Significantly higher (P < 0.001) mean levels of triglycerides (x = 192.1 mg/dl, SD ± 113.5) and total cholesterol (x = 212.9 mg/dl, SD ± 49.78) were observed in breast cancer as compared to controls or cervical cancer patients. Patients with cervical cancer had low mean values of all lipid fractions. Women with the above malignancies also showed a significantly decreased CD3+ and CD4+ population (P < 0.001), while there was a significant increase in CD8+ cells (P < 0.005) compared to normal controls. Interestingly, a significant relationship (P < 0.05) was observed between CD8+cells and LDL-cholesterol among the cancer patients (r = 0.3652 and r = 0.4298 for carcinomas of breast and cervix, respectively).

Body mass index, tumor characteristics, and prognosis following diagnosis of early-stage breast cancer in a mammographically screened population

PURPOSE

Many studies suggest increased body mass index (BMI) is associated with worse breast cancer outcomes, but few account for variability in screening, access to treatment, and tumor differences. We examined the association between BMI and risk of breast cancer recurrence, breast cancer-specific mortality, and all-cause mortality, and evaluated whether tumor characteristics differ by BMI among a mammographically screened population with access to treatment.

METHODS

Using a retrospective cohort study design, we followed 485 women aged ≥40 years diagnosed with stage I/II breast cancer within 24 months of a screening mammogram occurring between 1988 and 1993 for 10-year outcomes. BMI before diagnosis was categorized as normal (<25 kg/m(2)), overweight (25-29.9 kg/m(2)), and obese (≥30 kg/m(2)). Tumor marker expression was assessed via immunohistochemistry using tissue collected before adjuvant treatment. Medical records were abstracted to identify treatment, recurrence, and mortality. We used Cox proportional hazards to separately model the hazard ratios (HR) of our three outcomes by BMI while adjusting for age, stage, and tamoxifen use.

RESULTS

Relative to normal-weight women, obese women experienced increased risk of recurrence (HR 2.43; 95 % CI 1.34-4.41) and breast cancer death (HR 2.41; 95 % CI 1.00-5.81) within 10 years of diagnosis. There was no association between BMI and all-cause mortality. Obese women had significantly faster growing tumors, as measured by Ki-67.

CONCLUSIONS

Our findings add to the growing evidence that obesity may contribute to poorer breast cancer outcomes, and also suggest that increased tumor proliferation among obese women is a pathway that explains part of their excess risk of adverse outcomes.

Established breast cancer risk factors by clinically important tumour characteristics

Breast cancer is a morphologically and clinically heterogeneous disease; however, it is less clear how risk factors relate to tumour features. We evaluated risk factors by tumour characteristics (histopathologic type, grade, size, and nodal status) in a population-based case-control of 2386 breast cancers and 2502 controls in Poland. Use of a novel extension of the polytomous logistic regression permitted simultaneous modelling of multiple tumour characteristics. Late age at first full-term birth was associated with increased risk of large (> 2 cm) tumours (odds ratios (95% confidence intervals) 1.19 (1.07-1.33) for a 5-year increase in age), but not smaller tumours (P for heterogeneity adjusting for other tumour features (Phet) = 0.007). On the other hand, multiparity was associated with reduced risk for small tumours (0.76 (0.68-0.86) per additional birth; Phet = 0.004). Consideration of all tumour characteristics simultaneously revealed that current or recent use of combined hormone replacement therapy was associated with risk of small (2.29 (1.66-3.15)) and grade 1 (3.36 (2.22-5.08)) tumours (Phet = 0.05 for size and 0.0008 for grade 1 vs 3), rather than specific histopathologic types (Phet = 0.63 for ductal vs lobular). Finally, elevated body mass index was associated with larger tumour size among both pre- and postmenopausal women (Phet = 0.05 and 0.0001, respectively). None of these relationships were explained by hormone receptor status of the tumours. In conclusion, these data support distinctive risk factor relationships by tumour characteristics of prognostic relevance. These findings might be useful in developing targeted prevention efforts.

Obesity and outcomes in premenopausal and postmenopausal breast cancer

PURPOSE

Obesity is associated with adverse outcomes in postmenopausal women with breast cancer. In premenopausal women, the association is less clear.

METHODS

A population-based sample of 1,360 Australian women with breast cancer before the age of 60 years, 47% diagnosed before age 40, and 74% premenopausal, was studied prospectively for a median of 5 years (range, 0.2-10.8 years). Obesity was defined as a body mass index of > or =30 kg/m2. The hazard ratio (HR) for adverse clinical outcome associated with obesity was estimated using Cox proportional hazard survival models.

RESULTS

Obesity increased with age (P < 0.001) and was associated with increased breast cancer recurrence (P = 0.02) and death (P = 0.06), larger tumors (P = 0.002), and more involved axillary nodes (P = 0.003) but not with hormone receptor status (P > or = 0.6) or with first cycle adjuvant chemotherapy dose reductions (P = 0.1). Adjusting for number of axillary nodes, age at diagnosis, tumor size, grade, and hormone receptor status, obese women of all ages were more likely than nonobese women to have disease recurrence [HR, 1.57; 95% confidence interval (95% CI), 1.11-2.22; P = 0.02] and to die from any cause during follow-up (HR, 1.56; 95% CI, 1.01-2.40; P = 0.05). In premenopausal women, the adjusted HRs were 1.50 (95% CI, 1.00-2.26; P = 0.06) and 1.71 (95% CI, 1.05-2.77; P = 0.04), respectively.

CONCLUSIONS

Obesity is independently associated with poorer outcomes in premenopausal women, as it is in postmenopausal women, and this is not entirely explained by differences in tumor size or nodal status. Given the high and increasing prevalence of obesity in western countries, more research on improving the treatment of obese breast cancer patients is warranted.

Effects of obesity on breast cancer stage at diagnosis in Korean women

This study was carried out to test the hypothesis that palpation for lumps may be more difficult in large breasts than in small breasts, resulting in a delay in the detection and diagnosis of breast cancer, and to determine whether this hypothesis is confirmed in Asian women. Of 833 new breast cancer patients registered in the Daegu Cancer Registry in 1997-1999, 579 were used in the final data analysis, after excluding patient records containing many missing data on study variables related with cancer staging. There was no difference in means of body mass index (BMI) according to tumour, either in all cases or in those under 49 years of age. In the 50+ age group, the means+/-standard deviations of BMI of T1, T2 and T3 were 23.7+/-2.8, 24.2+/-3.0, and 26.2+/-4.3, respectively (P=0.01). In univariate logistic regression of tumour characteristics with BMI, no statistically significant odds ratios were found either by continuous or quartiles of BMI. In conclusion, these results suggest that the hypothesis is partially confirmed in Korean breast cancer patients and further studies are needed to clarify the relationship between BMI and tumour stage at diagnosis.

Factors influencing mortality among young women with second primary breast carcinoma

BACKGROUND

Tumor characteristics are strong predictors of survival among women with breast carcinoma, yet the variability in prognosis among women presenting with similar stages suggests other factors may also play an important role. We examine the prognostic significance of etiologic risk factors for breast carcinoma to determine whether factors that influence the development of breast carcinoma also affect the course of the disease among a prospective cohort of young women with bilateral breast carcinoma.

METHODS

The 369 U.S. women included in this study were from the Cancer and Steroid Hormone Study who were diagnosed with an invasive first primary breast carcinoma between 1980 and 1982 and a second primary breast carcinoma before 1999. Cox proportional hazards models were used to evaluate factors known and suspected to be associated with breast carcinoma and with survival, based on reporting at the time of the first primary.

RESULTS

One hundred sixty women died during the 16-18-year follow-up period. The adjusted 1, 5, 10, and 15-year survival rates following diagnosis of second primary breast carcinoma were 94%, 70%, 55%, and 49%, respectively. Survival rates werepoorest among the youngest women, those diagnosed with a second primary within 5 years of their first, poor African American women, women with either primary diagnosed at a later stage, those with less than 12 years of school, single women, and those with major weight gain between age 18 and adulthood.

CONCLUSIONS

This study provided little evidence that important etiologic factors for breast carcinoma predict mortality following diagnosis of a second primary breast carcinoma.

Body mass and stage of breast cancer at diagnosis

Obesity is a well-known risk factor for postmenopausal breast cancer. In contrast, the relationship between obesity and stage of breast cancer at diagnosis is less clear. We hypothesized that increased breast size in obese women may delay discovery of breast tumors. Thus, the purpose of our study was to examine whether there is an association between body mass and stage of breast cancer at diagnosis using hospital medical records. Newly diagnosed breast cancer cases (n = 966) in the Baltimore metropolitan area from 1991 to 1997 were included in our study. Patient information including age, ethnicity, weight, height and pathology data were obtained from hospital medical records. High body mass was significantly associated with late stage of breast cancer at diagnosis. Women who were obese (body mass index [BMI] > or = 27.3) were more likely to be at an advanced stage at diagnosis compared with women with a BMI of < 27.3 (multivariate-adjusted odds ratio [OR] 1.57, 95% confidence interval [CI] 1.15-2.14). The association between body mass and stage at diagnosis was stronger among women younger than 50 years (OR 2.34, 95% CI 1.34-4.08) compared with women 50 years or older (OR 1.30, 95% CI 0.89-1.91). Our study suggests that higher body mass is associated with advanced stage of breast cancer at diagnosis. This finding may be of considerable concern, given the increasing prevalence of obesity in women in the United States and the poor prognosis associated with late-stage tumors.

Relation of body mass index to tumor markers and survival among young women with invasive ductal breast carcinoma

BACKGROUND

Obesity has been shown to affect breast carcinoma prognosis, with the heaviest women having a higher mortality due to breast carcinoma. Few studies have focused on premenopausal women or the correlation of body mass index (BMI) to tumor characteristics related to prognosis.

METHODS

The authors conducted a population-based follow-up study for mortality of 1177 women younger than 45 years of age who had invasive ductal breast carcinoma diagnosed from 1983 through 1992. Histologic slides and/or tumor tissue were collected for pathologic review, immunohistochemistry assays, and bivariate flow cytometric analysis.

RESULTS

Women with breast carcinoma who were in the highest quartile of BMI were 2.5 times as likely (95% confidence interval [CI], 1.6-3.9) to die of their disease within 5 years of diagnosis compared with women in the lowest quartile of BMI. The tumors of the women in the highest quartile of BMI were more likely to be estrogen receptor negative (odds ratio [OR], 1.5; 95% CI, 1.0-2.2) and to have a high S-phase fraction (OR, 1.9; 95% CI, 1.2-3.1), high histologic grade (OR, 1.7; 95% CI, 1.0-2.9), high mitotic cell count (OR, 2.0; 95% CI, 1.2-3.1), and large tumor size (2 to < 5 cm: OR, 2.3; 95% CI, 1.5-3.1; or > or = 5 cm: OR, 2.7; 95% CI, 1.5-4.8) compared with the tumors of women whose BMI was in the first quartile. Relative to the large tumors (> or = 2 cm) in women in the lowest BMI quartile, the large tumors in women in the highest BMI quartile were more likely to express markers of high proliferation, indicating they may have grown faster than similar size tumors of the thinnest women. In a multivariate analysis including the tumor characteristics, obesity, as measured by being in the highest quartile of BMI, remained an independent prognostic factor for mortality (hazard ratio, 1.7; 95% CI, 1.0-2.9; P < 0.05.

CONCLUSIONS

Our study results indicated that being in the highest quartile of BMI was a strong predictor of mortality in women with breast carcinoma diagnosed at a young age. The tumors of the heavy women were larger and more likely to have markers of high cellular proliferation than those of thinner women.

Obesity affects expression of progesterone receptors and node metastasis of mammary carcinomas in postmenopausal women without a family history

Possible relationships between risk factors, such as obesity and a family history of breast cancer, and prognostic factors of mammary carcinomas were investigated by examining the body mass index of patients and the expression of estrogen (ER) and progesterone receptors (PgR), c-erbB-2 and p53, grade of histology, size of tumors and nodal status of mammary carcinomas. There was no significant difference in the body mass index of premenopausal patients either with or without a family history. For postmenopausal patients, the body mass index was significantly low in patients with a family history compared with patients without a family history. In premenopausal patients with or without a family history and in postmenopausal patients with a family history, there was no significant difference in the body mass index regardless of the mammary carcinoma prognostic factor, such as expression of ER, PgR, c-erbB-2 and p53, grade of histology, size of tumors and nodal status. However, in postmenopausal patients without a family history, body mass index was significantly high for patients with mammary carcinomas that had PgR expression and node metastasis. These results suggest that obesity may affect the PgR status and nodal status of mammary carcinomas in postmenopausal patients without a family history.

The effect of dietary exposures on recurrence and mortality in early stage breast cancer

We studied the effect of diet and body weight on recurrence and death in 472 women diagnosed with early-stage breast cancer in 1982-1984. From Cox proportional hazards regression models we found that the strongest effects were observed in premenopausal women. For example, after accounting for disease stage and age, reported baseline consumption (times/day) of butter, margarine, and lard (risk ratio (RR)=1.67; 95% confidence interval (CI)=1.17-2.39) and beer (drinks/day) (RR=1.58; 95% CI=1.15-2.17) increased the risk of recurrence. There also appeared to be an increased risk associated with consumption of red meat, liver, and bacon, corresponding to about a doubling of risk for each time per day that foods in this category were consumed (RR=1.93; 95 % CI=0.89-4.15). Relative body weight increased risk at the rate of 9% (RR=1.09; 95% CI=1.02-1.17) for each kg/m2 (equivalent to about 5.8 pounds for a woman 5'4" tall). For death, the results were similar, but relative weight was more strongly associated, increasing risk by 12% per kg/m2 (RR=1.12; 95% CI=1.03-1.22).

Serum cholesterol levels in patients with cancer. Relationship with nutritional status

Epidemiological surveys indicate an inverse relationship between cancer occurrence and serum cholesterol. Low serum cholesterol might be either a risk factor for cancer or the effect of factors associated with cancer itself, such as biological properties of malignant cells, tumor mass, and poor nutritional status. We have measured serum cholesterol in 975 selected patients admitted to our hospital; 496 (272 males, 224 females) had solid tumors and 479 (253 males, 226 females) had non-neoplastic diseases. Serum cholesterol was positively correlated with body mass index, serum albumin, hemoglobin, and cholinesterase in both cancer and non-cancer subjects. Cholesterol was significantly lower in cancer patients than in age- and sex-matched non-cancer subjects. After adjustment for nutritional variables (analysis of covariance), the difference in cholesterol level between cancer and non-cancer subjects lost statistical significance in all but patients with tumors of the upper gastrointestinal tract. No difference was found in adjusted mean serum cholesterol between cancer patients subdivided according to the extension of the tumor was defined by the TNM system. In patients with solid tumors, serum cholesterol seems to be more related to the nutritional status than the presence and extension of cancer.

Obesity and subcutaneous fat patterning in relation to survival of postmenopausal breast cancer patients participating in the DOM-project

The effect of obesity and fat distribution on survival of breast cancer patients was studied prospectively in 241 women with a natural menopause who participated in a breast cancer screening project, the DOM-project in Utrecht, The Netherlands. Mean follow-up time was 9.1 years and endpoint of interest was death from breast cancer. Fat distribution was assessed by contrasting groups of subscapular and triceps skinfold thickness. No significant differences in survival time between more obese (Quetelet's index > or = 26 kg/m2) and leaner (Quetelet's index < 26 kg/m2) patients or between patients with central fat distribution and patients with peripheral fat distribution were observed. Analyses were stratified by axillary node status, estrogen receptor status, and way of detection (by first screening or afterwards). Results of the stratified analyses were suggestive of a modifying effect of these factors. The absence of an association between obesity and survival time might be explained by two counteracting mechanisms. On the one hand obesity might be related to impaired survival, due to a tumor growth promoting effect of extra-ovarian estrogens. On the other hand obesity might be related to improved survival in a screened population, because obese patients profit more from screening by earlier detection of tumors than leaner counterparts.

A prospective study on obesity and subcutaneous fat patterning in relation to breast cancer in post-menopausal women participating in the DOM project

The associations of body fat and body fat distribution with breast cancer risk were examined in a prospective study in 9,746 post-menopausal women with a natural menopause, aged 49-66 at intake, participating in a breast cancer screening project (the DOM project in Utrecht). During a follow-up period of 15 years (mean follow-up time 12.5 years) 260 women developed breast cancer. Fat distribution, assessed by contrasting groups of subcapsular and triceps skinfold thickness, was found to be unrelated to breast cancer incidence. No significant relationship between body fat, measured either by weight, Quetelet's index, triceps skinfold or subscapular skinfold, and breast cancer risk was found when analysed in quartiles. However, women in the upper decile compared with the lower decile of the distribution of Quetelet's index were found to have a 1.9 times (95% CI 1.1-3.3) higher risk for breast cancer. These results seemed to be in contrast with the significant positive association between fatness, analysed in quartiles, and breast cancer observed in a cross-sectional study, based on mammographic screening, carried out previously in the same population. Although the differences between the present, prospective, study and our cross-sectional study may be due to chance it may be that there are differences between characteristics of breast cancer detected at screening and subsequently, which influence the associations between measures of fatness and risk of breast cancer.

Breast carcinoma and skeletal formation

We have studied skeletal structure in 67 women with breast carcinoma and in 59 women without breast carcinoma, looking for differences of development that might be correlated with hormonal, metabolic or genetic abnormalities. We have measured the lengths of the limbs and of their segments (upper arm, forearm, thigh, leg), of the bisacromial and bitrochanteric transverse diameters and total height and height divided into the parts from vertex to pubis and from pubis to the ground. The analysis showed statistically significant coefficients of regression with presence of mammary carcinoma for height (0.0904262, S.D. 0.0461), length of thigh (0.12989, S.D. 0.03981) and length of lower leg (-0.68475, S.D. 0.1390). This skeletal type might be the expression of a genetic condition that is associated with the existence of mechanisms that permit development of mammary cancer.

Biologic variations of tumors

Few tumors are so heterogeneous in their growth rates and patterns of metastasis as breast cancer. In general, the clinical phase of this disease is much longer than that of most other tumors. It is assumed that the preclinical phase is similarly long and this is one reason that the use of screening mammography has reduced breast cancer mortality. Mammography is not equally effective in all patient populations, but it has not yet been possible to precisely define those populations of women more or less likely to benefit from periodic mammography. Future studies should place greater emphasis on the correlation between frequency of mammography and biologic variations.

Obesity and body fat distribution and breast cancer prognosis

This study addresses the effect of obesity and body fat distribution on axillary lymph node involvement, tumor size, and estrogen receptor (ER) level in breast cancer patients. Anthropometric measurements were prospectively obtained on 248 consecutively and newly diagnosed women with invasive breast cancer. The anthropometric measurements evaluated were abdomen, thigh, subscapular, and midaxillary skinfolds; weight; and height. Weight and Quetelet Index (kg/m2) were significantly (P = 0.001) associated with lymph node involvement in postmenopausal patients. The abdomen:thigh skinfold ratio was significantly higher in premenopausal patients (P = 0.004) and postmenopausal (P = 0.03) without axillary node involvement compared with women with 4+ axillary node involvement. The abdomen:thigh skinfold was higher (P = 0.05) in women with smaller breast cancers (less than 2.0 cm) and higher ER levels. Weight and Quetelet Index did not affect tumor size or ER level. This study demonstrated that obese postmenopausal women who developed breast cancer tend to have more axillary node involvement than their leaner counterparts. Generalized obesity did not affect tumor size or ER level. Premenopausal and postmenopausal women with upper body fat distribution appear to be a subset of women who have a more favorable prognosis as measured by less lymph node involvement, smaller tumors, and higher levels of ER in their tumors.

Associations between breast cancer, plasma triglycerides, and cholesterol

A case-control study investigating the association between plasma lipids and breast cancer was conducted among women aged 30-80 in Buffalo, NY. All eligible women from a large breast clinic and two area physicians' offices were requested to participate over a one-year period. Subjects completed a health questionnaire and donated a fasting blood sample prior to diagnostic breast biopsies. The 83 women found to have breast cancer (cases) had significantly higher plasma triglyceride values than did the 113 women found not to have breast cancer (controls). Lower plasma beta-carotene values were associated with breast cancer, but only in those women with elevated triglyceride or cholesterol. Plasma cholesterol values were lower in those breast cancer cases presenting with more advanced stages of cancer, suggesting that metabolic effects of clinical and preclinical breast cancer may lower cholesterol levels. Although the limitations of case-control studies are well-recognized, these data suggest an etiologic role for plasma triglycerides and beta-carotene or for related dietary factors.

What can a woman do about her risk of dying of breast cancer?

Every day, American women are told that one in ten will develop breast cancer, and some groups perceive their risk to be so high as to justify immediate bilateral mastectomy. Many associations with breast cancer have been identified, including a history of benign breast diseases, in situ carcinoma, a family history of breast cancer, prolonged menstruation as a result of early menarche or delayed menopause, few or late pregnancies, excessive alcohol intake, obesity, and possibly the use of estrogens as oral contraceptives or postmenopausal replacement therapy. In spite of these associations, our understanding of either the cause(s) of breast cancer or the sequence of events leading to a diagnosis of breast cancer is still inadequate to make global public health recommendations regarding life style--or even to initiate well-designed studies. The epidemiologic evidence strongly suggests, however, that events relatively early in a woman's life are more important than later events, even though most of the risk of developing breast cancer will be expressed after the age of 75. Possibly one of the greatest contributions we can make to our patients' welfare is to share the knowledge that the risk of dying of breast cancer is considerably smaller than the risk of developing breast cancer; that the risk of early death from breast cancer rarely exceeds 10% in even the highest risk groups; and that the life styles most likely to reduce the risk of cardiovascular disease and other scourges of womankind are also those most likely to reduce the risk of developing breast cancer.

Energy balance, body size, and cancer

Increased energy intake and physical inactivity have been shown to heighten the risk of breast, large bowel, and other cancers. Large body size and fatness, as measured by adult stature, body weight and body mass indices, are positively related to a variety of cancers, including breast, colorectum, prostate, endometrium, kidney, and ovary, as well as to total cancer incidence or mortality in many investigations, although conflicting reports exist. Adult weight gain has also been specifically implicated in a few etiologic studies of breast and large bowel cancer. Furthermore, increased birthweight and childhood stature have been linked to increased risk of leukemia, lymphoma, osteogenic sarcoma, and central nervous system malignancies between infancy and young adulthood. Greater body weight also adversely affects breast cancer survival. These findings are complementary and support a role for positive energy balance in promoting human carcinogenesis. Potential mechanisms are discussed.

A proxy approach to the determination of total caloric intake for use in cancer epidemiology

In the absence of complete dietary information on a cohort of 472 early-stage breast cancer patients a caloric prediction technique was developed. Deriving an accurate caloric denominator would enable examination of individual nutrient effects by controlling for potential confounding by calories. Surrogate measures of mean daily caloric intake were generated from estimates of basal metabolic rate (BMR) predicted from age, height, weight, and physical activity. A validation study was undertaken to test the relationship between the BMR proxy terms and mean daily energy intake obtained from four-day food diaries for 51 subjects. Pearson correlation coefficients between the diary-derived and predicted values of caloric intake were computed (r = 0.43, p = 0.001). The results are in the range of what many researchers found when comparing self-reports of total caloric intake in validation and reliability studies of various dietary assessment tools. Because of the large heterogeneity of results across the ages represented in this study (25-77 yrs), it is recommended that small validation studies of this type be carried out in the subpopulations of interest.

Nutritional factors and cancers of the breast, endometrium and ovary

From an overview of epidemiological evidence on nutrition, diet and cancers of the breast, endometrium and ovary, the following indications can be drawn: Overweight and obesity are causally related to endometrial and post-menopausal breast cancer, and may account for as much as one third of the cases of endometrial and one tenth of breast cancer in Europe. It is not known whether obesity or overweight early in life has any role on breast cancer risk, nor whether obesity influences ovarian carcinogenesis. Overweight tends to be associated with an unfavourable prognosis for breast cancer. Despite extensive research, the available knowledge on diet and breast cancer is largely inconsistent, and the results from ecological and individual-based studies are contradictory in relation to fat, proteins, total energy, alcohol, etc. There are only scanty data on diet and endometrial or ovarian cancer, which tend to suggest role for fat (or animal fat) in the risk of these neoplasms. The evidence on diet and breast, ovarian and endometrial carcinogenesis is still too scanty or inconsistent to be of any practical preventive value. Thus, the only clear indication for prevention is that a reduction of overweight would avoid a substantial number of cases of endometrial and post-menopausal breast cancer.

Body size and menopausal status in relation to the pattern of spread in recurrent breast cancer

The prognosis and pattern of spread were related to body size and menopausal status in 863 patients with recurrent breast cancer. These patients were all enrolled in the adjuvant protocols of the Danish Breast Cancer Cooperative Group. The pattern of spread was illustrated by the number of metastases, the anatomical location of recurrence, and the rate of progression. Body size was estimated as height, weight, Quetelet index (QI), and body surface area (BSA). The body size was unassociated with both recurrence-free interval (RFI) and survival after recurrence (SAR). The groups of patients with different body size had both the same number and the same location of metastases. The tumour growth rates were estimated as clinical rates of progression (i.e. the time elapsed from a single distant metastasis until dissemination). The progression rate was unaffected by body size. Postmenopausal patients had a significantly shorter RFI and SAR compared to premenopausal patients. The number of metastatic sites, the anatomical location of metastases, and the rate of progression were similar in pre- and postmenopausal patients. The study could not confirm most findings from the literature which report a poor prognosis for patients with large body size. Moreover, the results do not suggest interactions between body size, menopausal status, and the clinical course of recurrent breast cancer.

Possible relevance of steroid availability and breast cancer

The as yet circumstantial evidence for a central role of estrogens in the promotion of human breast cancer is supported by many data. However, it has not been possible to identify breast cancer patients or women at risk by abnormally elevated estrogen levels in plasma. The concept of available, i.e., non-SHBG bound sex steroid seems to offer a better understanding than total serum steroid levels do. We demonstrated that sex steroid protein binding is decreased by free fatty acids. This finding may help to explain how the affluent Western diet and sedentary life style is related to high incidence rates of breast cancer. We have postulated that it is especially the central (abdominal) type of obesity which may increase sex steroid availability. This mechanism could be important already at the age of breast development when the sensitivity to promotion seems relatively great. It may also explain the increased incidence rates which are observed in Western industrialized countries after menopause. It seems likely that other endocrine-related cancer, such as endometrial or prostatic carcinomas are influenced in an analogous way.

Amount and type of fat/fiber in nutritional carcinogenesis

It is the totality of the evidence that links a high level of dietary fat to risk for breast and colon cancers. The evidence is built on descriptive epidemiology, correlation studies, migrant studies, time trends, case-control studies, metabolic epidemiology, experimental animal studies, and biological plausibility. The effects of total caloric intake or of obesity are not as relevant as the specific types and amounts of fat consumed. The effects of fiber in modulating colon cancer risk are inconsistent. This may be due, in part, to the varying effects of differing fibers. The key questions are, which fats and which fibers, and what amount of each, are of etiological and preventive significance?