The association between neighborhood-level income and cancer stage at diagnosis and survival in Alberta.

BACKGROUND: Socioeconomic status (SES) is associated with a range of health outcomes, including cancer diagnosis and survival. However, the evidence for this association is inconsistent between countries with and without single-payer health care systems. In this study, the relationships between neighborhood-level income, cancer stage at diagnosis, and cancer-specific mortality in Alberta, Canada, were evaluated. METHODS: The Alberta Cancer Registry was used to identify all primary cancer diagnoses between 2010 and 2020. Average neighborhood income was determined by linking the Canadian census to postal codes and was categorized into quintiles on the basis of income distribution in Alberta. Multivariable multinomial logistic regression was used to model the association between income quintile and stage at diagnosis, and the Fine-Gray proportional subdistribution hazards model was used to estimate the association between SES and cancer-specific mortality. RESULTS: Out of the 143,818 patients with cancer included in the study, those in lower income quintiles were significantly more likely to be diagnosed at stage III (odds ratio [OR], 1.07; 95% CI [confidence interval], 1.06-1.09) or IV (OR, 1.12; 95% CI, 1.11-1.14) after adjusting for age and sex. Lower income quintiles also had significantly worse cancer-specific survival for breast, colorectal, liver, lung, non-Hodgkin lymphoma, oral cavity, pancreas, and prostate cancers. CONCLUSIONS: Disparities were observed in cancer outcomes across neighborhood-level income groups in Alberta, which demonstrates that health inequities by SES exist in countries with single-payer health care systems. Further research is needed to better understand the underlying causes and to develop strategies to mitigate these disparities.

Participation, barriers, and facilitators of cancer screening among LGBTQ+ populations: A review of the literature.

The LGBTQ+ community is at higher risk of certain cancers but is less likely to participate in screening programs or engage with preventive healthcare. Despite this, the barriers and facilitators to cancer screening are not well understood in this population. We conducted a literature review of research related to LGBTQ+ participation in cancer screening, as well as barriers and facilitators to participation. Following abstract and full-text screening, 50 studies were included in the final synthesis. Compared to their heterosexual counterparts, lesbian and bisexual women were less likely to participate in cervical cancer screening and mammography, but gay and bisexual men were more likely to participate in anal and colorectal cancer screening. Transgender individuals had lower rates of screening than cisgender individuals for all cancer types. Barriers to participation were found at the individual-, provider-, and administrator-level, and good communication with a healthcare provider was the strongest facilitator. These results provide reasonable first steps toward improving participation rates for LGBTQ+ populations in cancer screening. Patient-centered approaches should draw on core guiding principles to inform the provision of care, including anticipating LGBTQ+ patients, improving knowledge about care for these patients, and confronting individually-held biases that may affect care, in order to improve care experiences and participation rates in preventive services.

Impact of the COVID-19 pandemic on cancer diagnoses, stage and survival in Alberta.

BACKGROUND: The COVID-19 pandemic is suspected to have affected cancer care and outcomes among patients in Canada. In this study, we evaluated the impact of the state of emergency period during the COVID-19 pandemic (Mar. 17 to June 15, 2020) on cancer diagnoses, stage at diagnosis and 1-year survival in Alberta. METHODS: We included new diagnoses of the 10 most prevalent cancer types from Jan. 1, 2018, to Dec. 31, 2020. We followed patients up to Dec. 31, 2021. We used interrupted time series analysis to examine the impact of the first COVID-19-related state of emergency in Alberta on the number of cancer diagnoses. We used multivariable Cox regression to compare 1-year survival of the patients who received a diagnosis during 2020 after the state of emergency with those who received a diagnosis during 2018 and 2019. We also performed stage-specific analyses. RESULTS: We observed significant reductions in diagnoses of breast cancer (incidence rate ratio [IRR] 0.67, 95% confidence interval [CI] 0.59-0.76), prostate cancer (IRR 0.64, 95% CI 0.56-0.73) and colorectal cancer (IRR 0.64, 95% CI 0.56- 0.74) and melanoma (IRR 0.57, 95% CI 0.47-0.69) during the state of emergency period compared with the period before it. These decreases largely occurred among early-stage rather than late-stage diagnoses. Patients who received a diagnosis of colorectal cancer, non-Hodgkin lymphoma and uterine cancer in 2020 had lower 1-year survival than those diagnosed in 2018; no other cancer sites had lower survival. INTERPRETATION: The results from our analyses suggest that health care disruptions during the COVID-19 pandemic in Alberta considerably affected cancer outcomes. Given that the largest impact was observed among early-stage cancers and those with organized screening programs, additional system capacity may be needed to mitigate future impact.

The efficacy of chemopreventive agents on the incidence of colorectal adenomas: A systematic review and network meta-analysis.

Colorectal cancer (CRC) is the fourth most common cancer and third leading cause of cancer-related death worldwide. Use of chemopreventive agents (CPAs) to reduce the incidence of precursor colorectal adenomas could lower the future burden of CRC. Many classes of potential CPAs have been investigated. To identify the most effective CPAs, we conducted a systematic review and a network meta-analysis (NMA). An electronic search was performed through August 2020 to identify all randomized controlled trials (RCTs) assessing the efficacy of CPAs in reducing the incidence of colorectal adenomas at the time of surveillance colonoscopy among patients who had previously undergone polypectomy during an index colonoscopy. In total, 33 RCTs were included in the NMA, which was conducted under a Bayesian inference framework. Random effects models were used with adjustment for follow-up length and control group event rates to yield relative risks (RRs) and 95% credible intervals (CrIs). Our full network consisted of 13 interventions in addition to a placebo arm. Of 20,925 included patients, 7766 had an adenoma. Compared to placebo, the combination of difluoromethylornithine (DFMO) + Sulindac (RR 0.24, CrI 0.10-0.55) demonstrated a protective effect, while aspirin had a RR of 0.77 (CrI 0.60-1.00), celecoxib 800 mg had a RR of 0.56 (CrI 0.31-1.01) and metformin had a RR of 0.56 (CrI 0.22-1.39). Our results suggest that select CPAs may be efficacious in preventing the development of adenomas. Further studies are needed to identify those patients most likely to benefit and the minimum effective dosages of CPAs.

One-year urinary and sexual outcome trajectories among prostate cancer patients treated by radical prostatectomy: a prospective study.

BACKGROUND: To examine one-year trajectories of urinary and sexual outcomes, and correlates of these trajectories, among prostate cancer patients treated by radical prostatectomy (RP). METHODS: Study participants were recruited from 2011 to 2014 at two US institutions. Self-reported urinary and sexual outcomes were measured at baseline before surgery, and 5 weeks, 6 months and 12 months after surgery, using the modified Expanded Prostate Cancer Index Composite-50 (EPIC-50). Changes in EPIC-50 scores from baseline were categorized as improved (beyond baseline), maintained, or impaired (below baseline), using previously-reported minimum clinically important differences. RESULTS: Of the 426 eligible participants who completed the baseline survey, 395 provided data on at least one EPIC-50 sub-scale at 5 weeks and 12 months, and were analyzed. Although all mean EPIC-50 scores declined markedly 5 weeks after surgery and then recovered to near (incontinence-related outcomes) or below (sexual outcomes) baseline levels by 12 months post-surgery, some men experienced improvement beyond their baseline levels on each sub-scale (3.3-51% depending on the sub-scale). Having benign prostatic hyperplasia (BPH) at baseline (prostate size ≥ 40 g; an International Prostate Symptom Index Score ≥ 8; or using BPH medications) was associated with post-surgical improvements in voiding dysfunction-related bother at 5 weeks (OR = 3.9, 95% CI: 2.1-7.2) and 12 months (OR = 3.3, 95% CI: 2.0-5.7); and in sexual bother at 5 weeks (OR = 5.7, 95% CI:1.7-19.3) and 12 months (OR = 3.0, 95% CI: 1.2-7.1). CONCLUSIONS: Our findings provide additional support for considering baseline BPH symptoms when selecting the best therapy for early-stage prostate cancer.

Emerging cancer incidence trends in Canada: The growing burden of young adult cancers.

BACKGROUND: Recent studies have identified increases in cancer incidence among younger adults for some cancers. This study examined incidence trends for 28 cancers in Canada by age and birth cohort from 1983 to 2012. METHODS: Canadian incidence data for 20 to 84 year-olds were obtained from the Cancer Incidence in Five Continents Plus database. Age-period-cohort modeling was used to estimate the average annual percentage changes (AAPCs) and incidence rate ratios (IRRs) for 10-year birth cohorts (reference cohort, 1943) for 28 cancer types. RESULTS: Incidence increased for 13 cancer sites among adults younger than 50 years (1983-2012), with the largest increase occurring for rectal cancer (AAPC20-24 , 5.62; 95% confidence interval [CI], 3.77-7.51) and colon cancer (AAPC20-24 , 4.08; 95% CI, 2.89-5.29). Compared with the 1943 birth cohort, persons born circa 1988 had approximately 5- and 2-fold greater risks of rectal cancer (IRR, 4.98; 95% CI, 2.87-8.63) and colon cancer (IRR, 2.31; 95% CI, 1.62-3.30), respectively. Incidence decreased among younger adults for 9 sites (1983-2012), with the largest decreases observed for lung cancer (AAPC25-29 ,-2.29; 95% CI, -3.57 to -0.98), cervical cancer (AAPC25-29 , -1.29; 95% CI, -1.67 to -0.90), and melanoma (AAPC25-29 , -0.61; 95% CI, -0.97 to -0.24). Decreased risks in recent birth cohorts were observed for all sites with decreasing trends in younger adults. For example, the risk of lung cancer was 60% lower in the 1988 birth cohort than the 1943 birth cohort (IRR, 0.42; 95% CI, 0.23-0.78). CONCLUSIONS: Incidence among young adults is increasing for some cancers associated with obesity but decreasing for many cancers associated with infections or smoking. Although further studies are needed to replicate these findings and understand the etiology of early-onset cancers, measures to promote healthy behaviors in young adults warranted.

Case-control study of endogenous sex steroid hormones and risk of endometrial cancer.

BACKGROUND: Epidemiologic evidence regarding the role of endogenous sex hormones in endometrial cancer etiology remains inconsistent. The objective of this study was to investigate if circulating levels of endogenous estrone, estradiol, sex hormone binding globulin (SHBG), testosterone, and androstenedione are associated with endometrial cancer risk. METHODS: We conducted a population-based case-control study of 522 incident endometrial cancer cases and 976 population controls, in Alberta, Canada from 2002 to 2006. Study participants completed in-person interviews and provided fasting blood samples. Sex hormone levels were determined by enzyme-linked immunosorbent assays. RESULTS: Higher levels of androstenedione were associated with increased endometrial cancer risk (OR 1.44, 95% CI 1.04-2.02). Endometrial cancer risk in pre- and peri-menopausal women was reduced for the highest versus lowest quartiles of estrone (OR 0.44, 95% CI 0.22-0.88) and estradiol (OR 0.30, 95% CI 0.14-0.65), but in post-menopausal women, the endometrial cancer risk was increased for the highest versus lowest quartile of androstenedione (OR 1.82, 95% CI 1.25-2.65). In addition, endometrial cancer risk in normal/underweight women was decreased for the highest versus lowest quartile of serum SHBG (OR 0.39, 95% CI 0.19-0.84). CONCLUSIONS: Overall, positive associations were found for androstenedione concentrations, while sub-group analyses revealed = inverse associations with estrogens and SHBG. Results of this study provide empirical evidence for the role of circulating sex hormones in endometrial cancer etiology and highlight the importance of modifiable factors that contribute to changes in sex hormone concentration levels.

Age-standardized cancer-incidence trends in Canada, 1971-2015.

BACKGROUND: Although cancer incidence over time is well documented in Canada, trends by birth cohort and age group are less well known. We analyzed age- and sex-standardized incidence trends in Canada for 16 major cancer sites and all cancers combined. METHODS: We obtained nationally representative population-based cancer incidence data in Canada between 1971 and 2015 from the National Cancer Incidence Reporting System (1969-1992) and the Canadian Cancer Registry (1992-2015). We analyzed cancer-incidence trends, reported as annual percent change (APC) for each 10-year group from age 20 to 89 years. We also estimated age-adjusted incidence rate ratios from fitted birth cohort models. RESULTS: Across most age categories, the most recent trends show significant decreases in the incidence of cervical (APC -8.8% to -0.33%), lung (men: -7.42% to -0.36%; women: -6.27% to 1.07%), bladder (women: -4.12% to -0.07%; men: -5.13% to -0.38%) and prostate cancer (-11.11% to -1.11%). Significant increasing trends were observed for kidney, thyroid and uterine cancers. Overall incidence has increased among both sexes younger than 50 years of age, with recent increases in pancreatic cancer among men, breast cancer among women and colorectal cancer among both sexes. From the birth cohort analysis, we observed increasing trends in colorectal, liver and prostate cancers among men; kidney cancer and melanoma among women; and thyroid cancer among both sexes. We observed decreasing trends in cervical and ovarian cancers, and in bladder and lung cancers among men. INTERPRETATION: Cancer incidence is decreasing at many sites targeted by primary-prevention efforts, such as smoking cessation and screening programs. Substantial increases in incidence among younger populations are driven by cancers possibly associated with obesity.

Overrepresentation of New Workers in Jobs with Multiple Carcinogen Exposures in Canada.

Background. In Canada, understanding the demographic and job-related factors influencing the prevalence of new workers and their exposure to potential carcinogens is crucial for improving workplace safety and guiding policy interventions. Methods. Logistic regression was performed on the 2017 Labour Force Survey (LFS), to estimate the likelihood of being a new worker based on age, industry, occupation, season, and immigration status. Participants were categorized by sector and occupation using the North American Industry Classification System (NAICS) 2017 Version 1.0 and National Occupational Classification (NOC) system 2016 Version 1.0. Finally, an exposures-per-worker metric was used to highlight the hazardous exposures new workers encounter in their jobs and industries. Results. Individuals younger than 25 years had 3.24 times the odds of being new workers compared to those in the 25-39 age group (adjusted odds ratios (OR) = 3.24, 95% confidence interval (95% CI) = 3.18, 3.31). Recent immigrants (less than 10 years in the country) were more likely to be new workers than those with Canadian citizenship (OR 1.36, 95% CI: 1.32, 1.41). The total workforce exposures-per-worker metric using CAREX Canada data was 0.56. By occupation, new workers were the most overrepresented in jobs in natural resources and agriculture (20.5% new workers), where they also experienced a high exposures-per-worker metric (1.57). Conclusions. Younger workers (under 25 years) and recent immigrants who had arrived 10 or fewer years prior were more likely to be new workers, and were overrepresented in jobs with more frequent hazardous exposures (Construction, Agriculture, and Trades).

Age-specific colorectal cancer incidence trends in Canada, 1971-2021.

INTRODUCTION: Colorectal cancer (CRC) incidence among adults younger than 50 years has increased in recent decades, leading to some advocating for lowering the age to start CRC screening. Here, we estimate age-specific trends in CRC incidence in Canada and changes in risk by birth cohort. METHODS: CRC incidence data from 1971 to 2021 by province, sex, and five-year age group (35-64) were obtained from the National Cancer Incidence Reporting System and the Canadian Cancer Registry. Annual percent changes in age-specific or age-adjusted incidence rates were analyzed with joinpoint regression. Birth cohort effect was estimated with age-period-cohort models and reported as cohort incidence rate ratios (IRRs) with respect to the 1947-51 cohort. RESULTS: CRC incidence has increased among all age groups under 50 years, with the largest relative increases occurring in the youngest age group (35-39 years). Males and females had similar incidence trends, though males under age 50 had larger increases than females. The birth cohort analysis showed that males born since 1966 have a significantly higher risk than those born at any other time. CONCLUSIONS: These results up to 2021 confirm and update reports that CRC incidence is increasing among adults under age 50 in Canada and that the youngest birth cohorts carry the highest risk. Future studies should assess the effectiveness of CRC screening in younger populations.

Performance of the fecal immunochemical test for colorectal cancer and advanced neoplasia in individuals under age 50.

The increased demand for colonoscopy combined with increased incidence of colorectal cancer (CRC) among younger populations presents a need to determine FIT performance among individuals in this age group. We conducted a systematic review to assess test performance characteristics of FIT in detecting CRC and advanced neoplasia in younger age populations. A search through December 2022 identified published articles assessing the sensitivity and specificity of FIT for advanced neoplasia or CRC among populations under age 50. Following the search, 3 studies were included in the systematic review. Sensitivity to detect advanced neoplasia ranged from 0.19 to 0.36 and specificity between 0.94 and 0.97 and the overall sensitivity and specificity were 0.23 (0.17-0.30) and 0.96 (0.94-0.98), respectively. Two studies that assessed these metrics in multiple age categories found similar sensitivity and specificity across all age groups 30-49. Sensitivity and specificity to detect CRC was assessed in one study and found no significant differences by age groups. These results suggest that FIT performance may be lower for younger individuals compared to those typically screened for CRC. However, there were few studies available for analysis. Given increasing recommendations to expand screening in younger age groups, more research is needed to determine whether FIT is an adequate screening tool in this population.

The Instagram Infodemic Persists: Extreme Content Escapes Platform's Removal Tactics.

The general cobranding of conspiracy theories and COVID-19 misinformation has been shared at an alarming rate on social media platforms. Instagram has attempted an initiative to flag and/or remove health misinformation and/or disinformation; however, the efficacy of these efforts has been unclear. This study aimed to re-examine 300 posts collected in a previous study evaluating trends in misinformation removal process on Instagram. One hundred eighty-three of 300 original posts remained on the platform, most of which were from the hashtag #hoax. Only one post was flagged for containing false information, despite presence in more than one post. The claims that the platform is removing or flagging misinformation does not align with these findings and amplifies the concern for public safety for Instagram users. Sharing and removal patterns among the 300 posts suggest that conspiracy theorists or those exposed to the inaccurate information may be at higher risk of believing and propagating other unsupported theories.

Dietary patterns with combined and site-specific cancer incidence in Alberta's Tomorrow Project cohort.

BACKGROUND/OBJECTIVES: Poor diet quality has been associated with an increased risk of cancer. Here, we examine the association between dietary patterns derived with two methods, and combined and site-specific cancer incidence in Canada. SUBJECTS/METHODS: Dietary data were obtained from participants enrolled in Alberta's Tomorrow Project, a prospective cohort study, between 2000 and 2008. Principle component analysis (PCA) and reduced rank regression (RRR) were used to derive dietary patterns, and data linkage with the Alberta Cancer Registry was used for incident cancer cases. Cox proportional hazard regressions were used to estimate multivariable-adjusted models for the association between each dietary pattern score with combined and site-specific cancer incidence. RESULTS: PCA revealed three dietary patterns ("western", "prudent", and "sugar, fruits, and dairy") and RRR resulted in four patterns ("dietary fiber", "vitamin D", "fructose", and "discretionary fat"). Five cancer sites were included in our site-specific analysis: lung, colon, breast, prostate, and endometrial cancers. The most protective dietary patterns for combined cancer sites were the "Prudent" pattern (HR = 0.82, CI = 0.73-0.92) and the "Dietary fiber" pattern (HR = 0.82, CI = 0.69-0.97). The "Fructose" pattern was associated with increased risk of combined cancers (HR = 1.14, CI = 1.02-1.27). Three dietary patterns were protective against colon cancer ("Prudent", "Dietary fiber", and "Discretionary fats"), and other risk reductions were seen for the "sugar, fruit, and dairy" pattern (lung cancer), and the "Dietary fiber" pattern (prostate cancer). CONCLUSIONS: These results support cancer prevention strategies for a diet high in vegetables, fruits, fish, and whole grains. Further studies should explore the possible association between discretionary fats and colon cancer.

Prevalence of Physical Health, Mental Health, and Disability Comorbidities among Women Living with HIV in Canada.

Life expectancy for people living with HIV has increased, but management of HIV is now more complex due to comorbidities. This study aimed to measure the prevalence of comorbidities among women living with HIV in Canada. We conducted a cross-sectional analysis using data from the 18-months survey (2014−2016) of the Canadian HIV Women's Sexual and Reproductive Health Cohort Study (CHIWOS). Self-report of diagnosed conditions was used to measure lifetime prevalence of chronic physical conditions, current mental health conditions, and disabilities. We examined frequency of overlapping conditions and prevalence stratified by gender identity, ethnicity, and age. Among 1039 participants, 70.1% reported a physical health diagnosis, 57.4% reported a current mental health diagnosis, 19.9% reported a disability, and 47.1% reported both physical and mental health comorbidities. The most prevalent comorbidities were depression (32.3%), anxiety (29.5%), obesity (26.7%, defined as body mass index >30 kg/m2), asthma/chronic obstructive pulmonary disease (23.3%), sleep disorder (22.0%), drug addiction (21.9%), and arthritis/osteoarthritis (20.9%). These results highlight the complexity of HIV care and the important prevalence of comorbidities. Personalized health care that integrates care and prevention of all comorbidities with HIV, with attention to social determinants of health, is necessary to optimize health and well-being of women living with HIV.

Effects of Exercise on Cancer Treatment Efficacy: A Systematic Review of Preclinical and Clinical Studies.

We systematically reviewed and synthesized evidence on the impact of physical activity/exercise on cancer treatment efficacy. We included six preclinical and seven clinical studies. Exercise significantly enhanced the efficacy of chemotherapy and tamoxifen in seven of eight rodent models in either an additive, sensitizing, or synergistic manner. In clinical studies, preliminary evidence indicates that exercise during neoadjuvant, primary, and adjuvant treatment may enhance efficacy of cancer therapies; however, no clinical study was designed for this purpose. Here we discuss the biological mechanisms of exercise-associated enhancement of therapeutic efficacy and propose future research directions to definitively examine the effects of exercise on cancer treatment and patient outcomes.

Trends in incidence of anal cancer in Austria, 1983-2016.

BACKGROUND: Recent reports have noted increasing rates of anal cancer among high-income countries worldwide; however, little is known about these trends in Austria. METHODS: Data on anal cancer from 1983 to 2016 were obtained from Statistics Austria. All tumors (n = 3567) were classified into anal squamous cell carcinomas (ASCC), anal adenocarcinomas (AADC), and others (unspecified carcinoma and other specific carcinoma). Anal cancer incidence rates were calculated in 5­year cycles and incidence average annual percentage change (AAPC) to evaluate trends by sex, histology and age group. RESULTS: The incidence rate of anal cancer was higher among females than males (relative risk, RR = 1.66, 95% confidence interval, CI: 1.55-1.79, p < 0.0001). From 1983 through 2016, incident anal cancer increased significantly (0.92 per 100,000 person-years to 1.85 per 100,000 person-years, AAPC = 1.93, 95% CI: 1.52 to 2.34, p < 0.0001), particularly among those 40-69 years old. From 1983 through 2016, the increasing anal cancer incidence was primarily driven by ASCC (0.47-1.20 per 100,000 person-years, AAPC = 2.23, 95% CI: 1.58 to 2.88, p < 0.0001) and others (other than ASCC and AADC, AAPC = 1.78, 95% CI: 1.01-2.55), yet stable in AADC (AAPC = 0.88, 95% CI: -0.48-2.25). CONCLUSIONS: Despite being a rare cancer in Austria, the increase in anal cancer incidence rate from 1983 to 2016 was substantial, particularly in ASCC. The observed rising trends reflect the need to investigate associated risk factors that have increased over time to inform preventive measures.

The incidence of breast cancer in Canada 1971-2015: trends in screening-eligible and young-onset age groups.

OBJECTIVES: Breast cancer incidence has fluctuated considerably in Canada, with recent reductions in rates among screening-eligible women. However, incidence of early-onset and pre-menopausal breast cancer is understudied. We examined age-specific trends in breast cancer incidence between 1971 and 2015, as well as possible trends by birth cohort. METHODS: Incidence data were collected from the National Cancer Incidence Reporting System and the Canadian Cancer Registry, and annual percent changes were estimated using the Joinpoint Regression Program. Five-year birth cohort models were fit using the National Cancer Institute's web tool. RESULTS: Breast cancer incidence among women under age 40 has increased since 2000, while incidence under 50 has remained stable. Rates of post-menopausal breast cancer declined sharply and have recently plateaued. More recent birth cohorts are at a non-significantly increased risk of breast cancer compared with the reference, with an increasing upward trend. CONCLUSIONS: Rates of breast cancer may be increasing among younger women, and there is suggestive evidence that more recent birth cohorts are at increased risk of the disease. More research is needed into the risk factors for pre-menopausal breast cancer to support primary prevention efforts in this area.

Global burden and trends in premenopausal and postmenopausal breast cancer: a population-based study.

BACKGROUND: Breast cancer has distinct causes, prognoses, and outcomes and effects in patients at premenopausal and postmenopausal ages. We sought to assess the global burden and trends in breast cancer by menopausal status. METHODS: We did a population-based analysis of global breast cancer incidence and mortality among premenopausal and postmenopausal women. Menopausal status was defined using age as a proxy, whereby breast cancer cases or deaths at age 50 years or older were regarded as postmenopausal. Age-standardised breast cancer incidence and mortality in 2018 were calculated using GLOBOCAN data. Incidence trends for 1998-2012 were assessed in 44 populations from 41 countries using the Cancer in Five Continents plus database, by calculating the annual average percent change. FINDINGS: Approximately 645 000 premenopausal and 1·4 million postmenopausal breast cancer cases were diagnosed worldwide in 2018, with more than 130 000 and 490 000 deaths occurring in each menopausal group, respectively. Proportionally, countries with a low UNDP human development index (HDI) faced a greater burden of premenopausal breast cancer for both new cases and deaths compared with higher income countries. Countries with a very high HDI had the highest premenopausal and postmenopausal breast cancer incidence (30·6 and 253·6 cases per 100 000, respectively), whereas countries with low and medium HDI had the highest premenopausal and postmenopausal mortality, respectively (8·5 and 53·3 deaths per 100 000, respectively). When examining breast cancer trends, we noted significantly increasing age-standardised incidence rates (ASIRs) for premenopausal breast cancer in 20 of 44 populations and significantly increasing ASIRs for postmenopausal breast cancer in 24 of 44 populations. The growth exclusively at premenopausal ages largely occurred in high-income countries, whereas the increasing postmenopausal breast cancer burden was most notable in countries under transition. INTERPRETATION: We provide evidence of a rising burden of both premenopausal and postmenopausal breast cancer worldwide. Although early diagnosis and access to treatment remain crucial in low-income and middle-income countries, primary prevention efforts seeking to decrease exposure to known breast cancer risk factors are warranted in all world regions to curb the future breast cancer burden. FUNDING: None.