Post-diagnosis weight change, physical activity, and survival among women with breast cancer: a longitudinal study with missing data

Nearly forty thousand women per year are diagnosed with breast cancer and there are currently over 2 million female breast cancer survivors in the United States. Whether survival after breast cancer diagnosis is influenced by modifiable lifestyle factors, including post-diagnosis weight change and physical activity, is unclear. These associations were examined using data from a population-based follow-up study of 1,508 women diagnosed with first primary in situ or invasive breast cancer between August 1, 1996 and July 31, 1997 in Long Island, New York. During baseline and follow-up interviews, women self-reported their height, weight, recreational physical activity levels and other factors. Additional information on clinical factors was ascertained through medical records and the New York State Cancer Registry. Vital status was determined using the National Death Index; through the end of 2005, 308 women were deceased, with 164 due to breast cancer. Approximately one-third of the subjects did not complete the follow-up interview. To address the issue of potentially non-ignorably missing data, I developed a selection model for survival analysis with time-varying covariates. A sensitivity analysis using the data on post-diagnosis weight change illustrated that a standard analysis resulted in reduced statistical efficiency and differences in magnitude of effect when compared to the selection model. Mortality was positively associated with both post-diagnosis weight loss and weight gain, regardless of the time since diagnosis or pre-diagnosis body size. More detailed analyses showed that previously reported associations of mortality with pre-diagnosis body mass index (BMI) and adult weight change were attenuated after accounting for post-diagnosis weight change, while associations with post-diagnosis weight change remained. Mortality was inversely associated with recreational physical activity, regardless of pre-diagnosis activity levels, timing of post-diagnosis activity, or pre-diagnosis BMI. Since weight gain and reduction in physical activity are common after breast cancer diagnosis, these findings that suggest weight maintenance and physical activity enhance survival among breast cancer survivors may be especially important

Adipose Tissue Distribution and Survival Among Women with Nonmetastatic Breast Cancer.

ObjectivePrevious studies of breast cancer survival have not considered specific depots of adipose tissue such as subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT).MethodsThis study assessed these relationships among 3,235 women with stage II and III breast cancer diagnosed between 2005 and 2013 at Kaiser Permanente Northern California and between 2000 and 2012 at Dana Farber Cancer Institute. SAT and VAT areas (in centimeters squared) were calculated from routine computed tomography scans within 6 (median: 1.2) months of diagnosis, covariates were collected from electronic health records, and vital status was assessed by death records. Hazard ratios (HRs) and 95% CIs were estimated using Cox regression.ResultsSAT and VAT ranged from 19.0 to 891 cm2 and from 0.484 to 454 cm2 , respectively. SAT was related to increased risk of death (127-cm2 increase; HR [95% CI]: 1.13 [1.02-1.26]), but no relationship was found with VAT (78.18-cm2 increase; HR [95% CI]: 1.02 [0.91-1.14]). An association with VAT was noted among women with stage II cancer (stage II: HR: 1.17 [95% CI: 0.99-1.39]; stage III: HR: 0.90 [95% CI: 0.76-1.07]; P interaction < 0.01). Joint increases in SAT and VAT were associated with mortality above either alone (simultaneous 1-SD increase: HR 1.19 [95% CI: 1.05-1.34]).ConclusionsSAT may be an underappreciated risk factor for breast cancer-related death

Body Mass Index, Weight Change, and Survival in Non-Hodgkin Lymphoma Patients in Connecticut Women

Evidence is emerging that obesity and weight gain may affect the prognosis of several types of cancer. We investigated the impact of body mass index (BMI) as well as pre- and post-diagnosis weight changes on non-Hodgkin lymphoma (NHL) prognosis

METABOLIC SYNDROME IN HEALTHY OBESE, OVERWEIGHT AND NORMAL WEIGHT INDIVIDUALS: THE ATHEROSCLEROSIS RISK IN COMMUNITIES STUDY

There is recent interest in characterizing the subset of obese individuals who have healthy metabolic profiles yet only two studies have examined this group prospectively but not in racially diverse populations. We analyzed factors associated with the prevalence and incidence of metabolic syndrome (MetSyn) among individuals grouped by body mass index (BMI) categories in a multi-center, community-based cohort of 14,663 African-American and white men and women aged 45-64 years at recruitment in 1987-1989, the Atherosclerosis Risk in Communities study. Logistic and proportional hazards regression were utilized to estimate odds ratios (OR) for the prevalence and hazard ratios (HR) for incidence of MetSyn with 95% confidence intervals (CI). At visit 1, MetSyn was positively associated with age, female gender, African-American race, and inversely related to education, associations being more pronounced among normal weight (NW) subjects. Among those without MetSyn at visit 1, obese (OB) subjects were more likely to develop MetSyn compared with NW [HR (95% CI): 4.53 (4.09-5.01)]. Several factors were associated with incident MetSyn among NW, including older age [per year: 1.05 (1.03-1.06)], female gender [vs. male: 1.29 (1.10-1.52)], heavy alcohol intake [vs. never: 0.75 (0.59-0.94)] and physical activity [tertile 3 vs. tertile 1: 0.71 (0.58-0.86)] but not OB. Weight gain (>5%) was also more highly associated with MetSyn in NW [1.61 (1.28-2.02)] compared with OB [1.01 (0.85-1.20)]. We conclude that lifestyle factors may play a stronger role in development of MetSyn in NW individuals compared with OB and that metabolically healthy obesity may not be a stable condition

Cardiovascular Disease Mortality Among Breast Cancer Survivors

Cardiovascular disease (CVD) is of increasing concern among breast cancer survivors. However the burden of this comorbidity in this group relative to the general population, and its temporal pattern, remains unknown

Risk Factors for Serrated Polyps of the Colorectum

Serrated pathway polyps are a relatively new area of interest in the field of colorectal cancer screening and prevention. Akin to conventional adenomas, some serrated polyps (SPs) have the potential to develop into malignant serrated neoplasms, yet little is known regarding risk factors for these lesions. Early epidemiological studies of hyperplastic polyps (HPs) were performed without knowledge of the serrated pathway, and likely included a mixture of SPs. More recently, studies have specifically evaluated premalignant SPs, such as the sessile serrated adenoma (SSA) or surrogates for these polyps such as large or proximally-located SPs. SPs share some risk factors with conventional adenomas, and have been associated with tobacco use, obesity, and age. Nonsteroidal anti-inflammatory drug (NSAID) use, fiber, folic acid, and calcium have been associated with reduced risk of SPs. Studies focused on SSAs specifically have reported associations with age, female sex, smoking, obesity, diabetes, and possibly diets high in fat, carbohydrates, and calories. Higher education has also been associated with risk of SSAs, while an inverse association between NSAID use and SSAs has been reported. Risk factors for traditional serrated adenomas (TSAs) are largely unknown. Studies are largely limited by varying inclusion criteria, as well as differences in pathological classification schemes. Further epidemiological studies of SPs are needed to aid in risk stratification and screening, and etiological research

A Bayesian proportional hazards regression model with non-ignorably missing time-varying covariates

Missing covariate data is common in observational studies of time to an event, especially when covariates are repeatedly measured over time. Failure to account for the missing data can lead to bias or loss of efficiency, especially when the data are non-ignorably missing. Previous work has focused on the case of fixed covariates rather than those that are repeatedly measured over the follow-up period, so here we present a selection model that allows for proportional hazards regression with time-varying covariates when some covariates may be non-ignorably missing. We develop a fully Bayesian model and obtain posterior estimates of the parameters via the Gibbs sampler in WinBUGS. We illustrate our model with an analysis of post-diagnosis weight change and survival after breast cancer diagnosis in the Long Island Breast Cancer Study Project (LIBCSP) follow-up study. Our results indicate that post-diagnosis weight gain is associated with lower all-cause and breast cancer specific survival among women diagnosed with new primary breast cancer. Our sensitivity analysis showed only slight differences between models with different assumptions on the missing data mechanism yet the complete case analysis yielded markedly different results

Use of Self-Care and Practitioner-Based Forms of Complementary and Alternative Medicine before and after a Diagnosis of Breast Cancer

Purpose. We examine factors associated with self-care, use of practitioner-based complementary and alternative medicine (CAM), and their timing in a cohort of women with breast cancer. Methods. Study participants were women with breast cancer who participated in the Long Island Breast Cancer Study Project. Self-care is defined as the use of multivitamins, single vitamins, botanicals, other dietary supplements, mind-body practices, special diets, support groups, and prayer. Within each modality, study participants were categorized as continuous users (before and after diagnosis), starters (only after diagnosis), quitters (only before diagnosis), or never users. Multivariable logistic regression was used for the main analyses. Results. Of 764 women who provided complete data, 513 (67.2%) initiated a new form of self-care following breast cancer diagnosis. The most popular modalities were those that are ingestible, and they were commonly used in combination. The strongest predictor of continuous use of one type of self-care was continuous use of other types of self-care. Healthy behaviors, including high fruit/vegetable intake and exercise, were more strongly associated with continuously using self-care than starting self-care after diagnosis. Conclusions. Breast cancer diagnosis was associated with subsequent behavioral changes, and the majority of women undertook new forms of self-care after diagnosis. Few women discontinued use of modalities they used prior to diagnosis

Polycystic ovarian syndrome (PCOS), related symptoms/sequelae, and breast cancer risk in a population-based case–control study

Despite the overlap between the clinical symptoms/sequelae of polycystic ovarian syndrome (PCOS) and many known reproductive risk factors for breast cancer, the relationship between PCOS and breast cancer remains unclear, possibly because of the complex heterogeneity and challenges in diagnosing PCOS over time. We hypothesized that PCOS, specific PCOS-related symptoms/sequelae, or clusters of PCOS-related symptoms/sequelae, may be differentially associated with pre- vs. postmenopausal breast cancer risk

Environmental Tobacco Smoke Exposure and Survival Following Breast Cancer

Environmental tobacco smoke (ETS) exposure is hypothesized to influence survival after breast cancer, but few studies have examined this association