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Key features: 

• The Northern Sweden Health and Disease Study (NSHDS) was initiated in the mid-1980s. The NSHDS is a population-based prospective longitudinal cohort comprising >140 000 participants in the two northernmost regions in Sweden, Norrbotten and Västerbotten, with >240 000 blood samples and 1.5 million person-years of follow-up.
• The NSHDS includes three sub-cohorts: the Västerbotten Intervention Programme (VIP), the expanded Northern Sweden Monitoring of Trends and Determinants of Cardiovascular Disease (MONICA) Study, and the Mammography Screening Project (MSP). The VIP is both a community-based cardiometabolic intervention programme encouraging healthy lifestyle (targeting individuals 40, 50, and 60 years of age), and a corresponding research cohort. The MONICA is an observational study focusing on cardiovascular disease and its associated risk factors, recruiting individuals aged 25–74 years. The MSP recruited women attending mammography during 1995–2006. The NSHDS median participation age is 50 years (53% women).
• Most participants contribute data on health, lifestyle, anthropometric measures, blood pressure, blood lipids, and glucose tolerance, along with research blood samples that are fractionated, frozen within an hour of collection, and stored at –80°C. Linkage to registries, clinical cohorts, and biological tissue archives facilitates studies of well-characterized participants (often combined with intervention studies).
• Collaborations are encouraged. Additional information can be found at: info.brs@umu.se; https://www.umu.se/en/biobank

Pancreatic ductal adenocarcinoma (PDAC) is associated with a poor prognosis, and biomarkers to guide treatment decisions in PDAC are generally lacking. Intratumoural expression of dihydropyrimidine dehydroge- nase (DPD) is a potential prognostic parameter in patients with PDAC undergoing surgical resection and postoperative chemotherapy. In the present study, DPD was analysed by immunohistochemistry of a tissue microarray platform including a real-world cohort of 495 patients with PDAC who had undergone resection with curative intent at any of three tertiary centres, including Northern, Western and Southeastern regions of Sweden, between 1993 and 2019. DPD level (high/low) was analysed and overall survival associations were assessed in treatment subgroups using a multivariate Cox regression model accounting for potential confounders. In patients who had not received adjuvant chemotherapy (n=182), the median overall survival time was 11.6 months (95% CI 9.6-13.5), compared with 28.8 months (25.0-32.6) among those who had (n=313; log-rank P<0.001). The most common type of chemotherapy was gemcitabine single agent (Gem, n=239) followed by gemcitabine plus capecitabine (GemCape, n=39). Tumour-Node-Metastasis (TNM) stage and DPD expression were statistically significant prognostic parameters in the Gem group (HR 1.19, 95% CI 1.01-1.41, P=0.036), with high expres- sion of DPD linked with worse survival. In addition, tumour grade and TNM stage were statistically significant prognostic factors in the group that did not receive any chemotherapy (P≤0.001). No statistically significant parameters were iden- tified in the GemCape group. Taken together, intratumoural expression of DPD may be considered a prognostic marker for patients with PDAC treated with adjuvant gemcitabine following surgical resection, with low expression levels predicting better survival. Further studies in larger cohorts of patients receiving multi-drug or non-gemcitabine based regimens are warranted.

Introduction: Observational studies suggest that breast conserving surgery (BCS) and radiotherapy (RT) offers superior survival compared to mastectomy. The aim was to compare patient and tumour characteristics in women with invasive breast cancer ≤30 mm treated with either BCS or mastectomy, and to explore the underlying reason for choosing mastectomy.

Methods: Women registered with breast cancer ≤30 mm and ≤4 positive axillary lymph nodes in the Swedish National Breast Cancer Register 2013–2016 were included. Logistic regression analyses were performed to assess the association of tumour and patient characteristics with receiving a mastectomy vs. BCS.

Results: Of 1860 breast cancers in 1825 women, 1346 were treated by BCS and 514 by mastectomy. Adjuvant RT was given to 1309 women (97.1 %) after BCS and 146 (27.6 %) after mastectomy. Variables associated with receiving a mastectomy vs. BCS included clinical detection (Odds Ratio (OR) 4.15 (95 % Confidence Interval (CI) 3.35–5.14)) and clinical stage (T2 vs. T1 (OR 3.68 (95 % CI 2.90–4.68)), N1 vs. N0 (OR 2.02 (95 % CI 1.38–2.96)). Women receiving mastectomy more often had oestrogen receptor negative, HER2 positive tumours of higher histological grade. The most common reported reason for mastectomy was large or multifocal tumours (53.5 %), followed by patient preference (34.5 %).

Conclusion: Choice of surgery is strongly associated with key prognostic factors among women undergoing BCS with RT compared to mastectomy. Failure to control for all relevant confounders may bias results in outcome studies in favour of BCS.

Background: Randomized trials have shown that axillary clearance (AC) can safely be omitted in patients with sentinel lymph node-positive breast cancer. At the same time, de-escalation of chemotherapy in postmenopausal patients with ER+HER2− breast cancer may depend on detailed axillary nodal stage. The aim of this pre-specified secondary analysis of the SENOMAC trial was to investigate whether the choice of axillary staging affected the proportion of patients receiving adjuvant chemotherapy, and recurrence-free survival (RFS).

Methods: Proportion receiving adjuvant chemotherapy was calculated according to AC or sentinel lymph node biopsy (SLNB) only, menopausal status, and region of inclusion, for 2168 patients with clinically node-negative ER+HER2− breast cancer and 1–2 sentinel lymph node macrometastases included in the SENOMAC trial.

Findings: In premenopausal patients, 514 out of 615 patients (83.6%) received adjuvant chemotherapy with no significant difference between randomization arms. In postmenopausal patients, the proportion receiving chemotherapy varied considerably by region and country (36.0–82.4%). In Denmark, where 194 out of 539 postmenopausal patients (36.0%) received adjuvant chemotherapy, rates differed significantly between the AC and the SLNB only arm (41.3% vs 31.4%, p = 0.019). After a median follow-up of 44.88 months for Danish postmenopausal patients, no significant difference was seen in 5-year RFS, which was 91% (85.6%–96.6%) for the SLNB only and 90.9% (86.3%–95.6%) for the AC arm (p = 0.42).

Interpretation: When omitting axillary clearance, and thus reducing the risk of long-term arm morbidity, potential under-treatment of postmenopausal patients with ER+HER2− breast cancer may require the development of new predictive and imaging tools.

Background: A high body mass index (BMI, kg/m2) is associated with decreased risk of breast cancer before menopause, but increased risk after menopause. Exactly when this reversal occurs in relation to menopause is unclear. Locating that change point could provide insight into the role of adiposity in breast cancer etiology.

Methods: We examined the association between BMI and breast cancer risk in the Premenopausal Breast Cancer Collaborative Group, from age 45 up to breast cancer diagnosis, loss to follow-up, death, or age 55, whichever came first. Analyses included 609,880 women in 16 prospective studies, including 9956 who developed breast cancer before age 55. We fitted three BMI hazard ratio (HR) models over age-time: constant, linear, or nonlinear (via splines), applying piecewise exponential additive mixed models, with age as the primary time scale. We divided person-time into four strata: premenopause; postmenopause due to natural menopause; postmenopause because of interventional loss of ovarian function (bilateral oophorectomy (BO) or chemotherapy); postmenopause due to hysterectomy without BO. Sensitivity analyses included stratifying by BMI in young adulthood, or excluding women using menopausal hormone therapy.

Results: The constant BMI HR model provided the best fit for all four menopausal status groups. Under this model, the estimated association between a five-unit increment in BMI and breast cancer risk was HR=0.87 (95% CI: 0.85, 0.89) before menopause, HR=1.00 (95% CI: 0.96, 1.04) after natural menopause, HR=0.99 (95% CI: 0.93, 1.05) after interventional loss of ovarian function, and HR=0.88 (95% CI: 0.76, 1.02) after hysterectomy without BO.

Conclusion: The BMI breast cancer HRs remained less than or near one during the 45–55 year age range indicating that the transition to a positive association between BMI and risk occurs after age 55.

Screening of the general population for cancer is a matter of primary prevention reducing the burden of disease. Whilst this is successful for several cancers including breast, colon and prostate, the situation to screen and hence prevent pancreatic cancer is different. The organ is not as accessible to simple physical exam or biological samples (fecal or blood test). Neither exists a blood test such as PSA that is cost-effective. Reviewing the evidence from screening risk groups for pancreatic cancer, one must conclude that there is no rational at present to screen the general population, for a lack of appropriate tests.

Background: In luminal breast cancer, adjuvant CDK4/6 inhibitors (eg, abemaciclib) improve invasive disease-free survival. In patients with T1–2, grade 1–2 tumours, and one or two sentinel lymph node metastases, completion axillary lymph node dissection (cALND) is the only prognostic tool available that can reveal four or more nodal metastases (pN2–3), which is the only indication for adjuvant abemaciclib in this setting. However, this technique can lead to substantial arm morbidity in patients. We aimed to pragmatically describe the potential benefit and harm of this strategy on the individual patient level in patients from the ongoing SENOMAC trial.

Methods: In the randomised, phase 3, SENOMAC trial, patients aged 18 years or older, of any performance status, with clinically node-negative T1–T3 breast cancer and one or two sentinel node macrometastases from 67 sites in five European countries (Denmark, Germany, Greece, Italy, and Sweden) were randomly assigned (1:1), via permutated block randomisation (random block size of 2 and 4) stratified by country, to either cALND or its omission (ie, they had a sentinel lymph node biopsy only). The primary outcome is overall survival, which is yet to be reported. In this post-hoc analysis, patients from the SENOMAC per-protocol population, with luminal oestrogen-receptor positive, HER2-negative, T1–2, histological grade 1–2 breast cancer, with tumour size of 5 cm or smaller were selected to match the characteristics of cohort 1 of the monarchE trial who would only have an indication for adjuvant abemaciclib if found to have 4 or more nodal metastases. The primary study objective was to determine the number of patients who developed patient-reported severe or very severe impairment of physical arm function after cALND (as measured by the Lymphedema Functioning, Disability, and Health [Lymph-ICF] Questionnaire) 1 year after surgery to avoid one invasive disease-free survival event at 5 years with 2 years of adjuvant abemaciclib, using invasive disease-free survival event data from cohort 1 of the monarchE trial. The SENOMAC trial is registered with ClincialTrials.gov, NCT02240472, and is closed to accrual and ongoing.

Findings: Between Jan 31, 2015, and Dec 31, 2021, 2766 patients were enrolled in SENOMAC and randomly assigned to cALND (n=1384) or sentinel node biopsy only (n=1382), of whom 2540 were included in the per-protocol population. 1705 (67%) of 2540 patients met this post-hoc study's eligibility criteria, of whom 802 (47%) had a cALND and 903 (53%) had a sentinel lymph node biopsy only. Median age at randomisation was 62 years (IQR 52–71), 1699 (>99%) of 1705 patients were female, and six (<1%) were male. Among 1342 patients who responded to questionnaires, after a median follow-up of 45·2 months (IQR 25·6–59·8; data cutoff Nov 17, 2023), patient-reported severe or very severe impairment of physical arm function was reported in 84 (13%) of 634 patients who had cALND versus 30 (4%) of 708 who had sentinel lymph node biopsy only (χ2 test p<0·0001). To avoid one invasive disease-free survival event at 5 years with adjuvant abemaciclib, cALND would need to be performed in 104 patients, and would result in nine patients having severe or very severe impairment of physical arm function 1 year after surgery.

Interpretation: As a method to potentially identify an indication for abemaciclib, and subsequently avoid invasive disease-free survival events at 5 years with 2 years of adjuvant abemaciclib, cALND carries a substantial risk of severe or very severe arm morbidity and so cALND should be discouraged for this purpose. Funding: Swedish Research Council, the Swedish Cancer Society, the Nordic Cancer Union, and the Swedish Breast Cancer Association.

Objective: In the last decade there has been increasing interest in defining pancreatic steatosis (PS) and establishing its association with pancreatic ductal adenocarcinoma (PDAC). However, no consensus guidelines have yet been published on the management of PS. In this systematic review and meta-analysis performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we investigated the association between PS and PDAC.

Design: Medical literature between 2007 and 2023 was reviewed for eligible trials investigating the prevalence of PS in patients with PDAC. Eligible studies reporting on PS, assessed via imaging or histology, were included. The primary objective was to determine the association between PDAC and PS by comparing the prevalence of PS in individuals with- and without PDAC. Secondary, an evaluation was conducted to establish whether the method of assessment correlated with the association of PDAC and PS, and the prevalence of PDAC in individuals with PS. Measures of effect size were determined using odds ratios (ORs) and corresponding 95 % confidence intervals (95 % CI).

Results: The systematic review identified a total of 23 studies, of which seventeen studies examined PS prevalence among PDAC patients and were included in the meta-analysis. Overall, the pooled prevalence of PS in patients with PDAC was 53.6 % (95 % CI 40.9–66.2). No significant difference in PS prevalence was observed across various diagnostic methods or geographical regions. Overall, the pooled OR for PS in patients with PDAC compared to controls was 3.23 (95 % CI 1.86–5.60).

Conclusions: PDAC patients have a high prevalence of PS, and they are significantly more likely to have PS compared to controls. These findings emphasize the need to prioritize a standardized approach to the diagnosis, follow-up, and treatment of PS, with future studies focusing on identifying patients who would benefit from PDAC surveillance programs.