Background: The association between dietary vitamin A intake and cancer risk remains unclear. There may be under-researched links between dietary vitamin A and cancer. This study aimed to clarify this relationship and a possible reference vitamin A intake. Methods: We conducted a hospital-based case–control study. Exposure data was determined from participants, including 3758 incident cancer cases (esophagus, stomach, colon, rectum, lung, breast, and other cancers) and 2995 hospital controls before the day of surgery treatment at the same hospitals. Dietary vitamin A intake was assessed using a validated semi-quantitative food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the association between vitamin A intake and cancer risk. Restricted cubic splines suggest a safe range of vitamin A intake of 85.3–104.0 µg/day, which is a reference quantile. Results: We found a U-shaped association between vitamin A intake and cancer incidence compared to the reference. Both the lowest and highest intakes were associated with an increased cancer risk, with OR (95% CI) values 1.98 (1.57, 2.49) and 2.06 (1.66, 2.56), respectively. This U-shaped pattern was consistent across subgroups defined by sex, body mass index, smoking status, alcohol consumption, blood type A, and cancers of the esophagus, stomach, breast, and rectum, but not lung and colon cancer. The U-shaped relationship remained after adjusting for dietary vitamin A intake per kg of body weight and vitamin A–energy residual estimation adjustment. Confidence intervals were wider at the highest exposure levels. Conclusions: We observed a U-shaped relationship between vitamin A intake and the risk of cancer incidence, with a reference dietary vitamin A intake of 85.3–104.0 µg/day. These findings warrant further investigation to understand the mechanisms of this U-shaped association.

Background: Lumboperitoneal (LP) shunt surgery is an established treatment for idiopathic normal pressure hydrocephalus (iNPH). In Japan, patients undergoing LP shunt surgery are often hospitalized for several days to more than one week after surgery, even in uncomplicated cases, reflecting concerns regarding early complications, cerebrospinal fluid overdrainage, and discharge readiness in older adults. This study evaluated the feasibility and short-term safety of a perioperative optimization pathway for planned short-stay hospitalization after LP shunt surgery. Methods: This single-center retrospective before-and-after cohort study included 15 consecutive patients who underwent elective LP shunt surgery. Six patients were managed using a conventional hospitalization pathway, whereas nine patients were treated under a short-stay pathway targeting discharge after one postoperative night. Key perioperative modifications included a uniform higher initial programmable valve pressure (level 7), structured discharge education, scheduled postoperative analgesia, waterproof wound sealing permitting early showering, and early outpatient follow-up with head computed tomography for staged valve pressure adjustment. The primary outcome was 30-day safety, defined as readmission, reoperation, or major postoperative complications. Results: Baseline characteristics were generally comparable between groups, although the short-stay group was slightly older and had more frequent antithrombotic therapy. Mean hospital length of stay was shorter in the short-stay group than in the conventional group (3.7 ± 2.0 vs. 9.7 ± 0.8 days; median, 3 vs. 9.5 days). Orthostatic headache requiring valve adjustment occurred in three conventional cases but in none of the short-stay patients. No patients in the short-stay group required readmission or reoperation within 30 days. Conclusions: In this pilot before-and-after study, a short-stay LP shunt pathway incorporating perioperative optimization and individualized discharge decision-making was feasible and was not associated with an apparent increase in early adverse events. These findings should be interpreted as exploratory and may support further evaluation of short-stay management strategies for selected patients undergoing LP shunt surgery in Japan.