Usman Saeed

• Aune, Dagfinn; Nordsletten, Marie Wiborg; Myklebust, Tor Åge; Robsahm, Trude Eid; Skålhegg, Bjørn Steen & Mala, Tom [Show all 8 contributors for this article] (2025). Body mass index and risk of Hodgkin's lymphoma: Insights from a Norwegian cohort study. European Journal of Cancer. ISSN 0959-8049. 221. doi: 10.1016/j.ejca.2025.115400. Full text in Research Archive Show summary

  Background Several studies have reported positive associations between higher body mass index (BMI) and risk of Hodgkin's lymphoma. However, the evidence is not entirely consistent. We investigated the association between BMI and Hodgkin's lymphoma in a large Norwegian cohort with up to 50 years follow-up. Methods The analytical dataset included 1723,692 men and women aged 16–75 years at baseline in 1963–1975. Multivariable Cox regression analyses were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) for the associations between BMI and Hodgkin's lymphoma incidence. Results During 56.1 million person-years of follow-up, 1608 incident Hodgkin's lymphoma cases occurred. Compared to individuals with BMI 18.5-< 25, the HRs (95 % CIs) for those with a BMI of 15-< 18.5, 25-< 30, and ≥ 30 were 0.87 (0.59–1.27), 1.05 (0.94–1.18), and 1.61 (1.35–1.91), respectively, and 1.57 (1.30–1.90) and 1.80 (1.24–2.62) for obesity grade 1 and grade 2, respectively. A positive association was also observed per 5 kg/m2 increment with a HR (95 % CI) of 1.16 (1.08–1.24) overall, 1.20 (1.09–1.31) in women, and 1.08 (0.96–1.20) in men. Positive associations were also observed between obesity vs. normal weight in early adulthood (age 16–29 years) and Hodgkin's lymphoma (HR, 95 % CIs: 1.89, 1.10–3.22, ptrend<0.0001, n = 489 cases) and between obesity and early-onset (age <50 years at diagnosis) disease (HR, 95 % CIs: 1.67, 1.01–2.78, ptrend<0.0001, n = 393 cases). Conclusion The positive associations observed between higher BMI overall and in young adulthood and Hodgkin's lymphoma and between BMI and early-onset disease emphasize the potential role of adiposity in development of this malignancy.

• Aune, Dagfinn; Nordsletten, Marie Wiborg; Myklebust, Tor Åge; Robsahm, Trude Eid; Skålhegg, Bjørn Steen & Mala, Tom [Show all 8 contributors for this article] (2025). Body mass index and risk of connective and soft tissue cancer: results from a large cohort of 1.7 million individuals in Norway. BMC Cancer. 25. doi: 10.1186/s12885-025-13637-8. Full text in Research Archive Show summary

  Background Few studies have investigated the association between adiposity and connective and soft tissue cancer, a rare and understudied cancer entity. We investigated this association in a large cohort of more than 1.7 million individuals in Norway. Methods The study cohort included 1,723,692 men and women aged 16–75 years at baseline in 1963–1975. Data on weight and height measurements from the Norwegian Tuberculosis Screening Programme were linked to the Cancer Registry. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between body mass index (BMI) and risk of connective and soft tissue cancer, adjusting for age and sex. Results In total 1758 connective and soft tissue cancer cases were registered during 56.1 million person-years of follow-up. The HRs (95% CIs) for the BMI categories of 15-<18.5, 18.5-<25.0 (reference), 25.0-<30.0, 30.0-<35.0, ≥ 35.0 were 0.77 (0.50–1.20), 1.00 (reference), 1.15 (1.03–1.27), 1.28 (1.06–1.54), and 1.69 (1.21–2.37, ptrend<0.0001). The HR per 5 kg/m2 increment in BMI was 1.14 (1.07–1.22) overall, 1.10 (0.99–1.23) in men and 1.17 (1.08–1.27) in women. Obesity in early adulthood (age 16–29 years) showed a suggestive positive association with connective and soft tissue cancer risk with HR (95%CIs) of 1.73 (0.95–3.16), ptrend=0.09) when compared to normal weight. No clear association was observed between BMI and early-onset (age < 50 years at diagnosis) connective and soft tissue cancer. Positive associations were observed between BMI and soft tissue sarcoma, fibrosarcoma, dermatofibroma, and lipoleiomyoma, but no clear associations were observed with fibrous histiocytoma and liposarcoma. Conclusion These results suggest that higher BMI overall and in early adulthood may be associated with increased risk of connective and soft tissue cancer, but BMI seems not to influence early-onset disease. Large cohort studies with more detailed information on confounding factors and BMI trajectories over time are needed for further verification before firm conclusions can be made.

• Aune, Dagfinn; Nordsletten, Marie Wiborg; Myklebust, Tor Åge; Robsahm, Trude Eid; Skålhegg, Bjørn Steen & Mala, Tom [Show all 8 contributors for this article] (2025). Body mass index and ampulla of Vater cancer incidence and survival: a cohort study of 1.7 million Norwegians. Hepatobiliary surgery and nutrition. ISSN 2304-3881. p. 1–8. doi: 10.21037/hbsn-2024-636. Full text in Research Archive Show summary

  Background: Although higher body mass index (BMI) has been associated with increased risk of hepatobiliary cancers in previous studies, the association with risk of ampulla of Vater cancer has rarely been reported. We therefore investigated the association between BMI and ampulla of Vater cancer incidence in a large Norwegian cohort. Methods: The analytical dataset included 1,723,692 men and women aged 16–75 years at baseline in 1963– 1975. Multivariable Cox regression analyses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between BMI and ampulla of Vater cancer incidence and survival. Results: During 56.1 million person-years of follow-up, a total of 814 cases with ampulla of Vater cancer were identified. Compared to participants with a BMI of 18.5–<25 kg/m2, the HRs (95% CIs) of those with a BMI of 15–<18.5, 25–<30, and ≥30 kg/m2 were 0.19 (0.05–0.77), 1.02 (0.88–1.19), and 1.03 (0.80–1.32), respectively, and 1.02 (0.92–1.12) per 5 kg/m2 increment. No association was observed in men and women, when analysed separately. The HRs (95% CIs) for BMI in young adulthood were 0.39 (0.10–1.57), 1.00, 1.26 (0.80–1.99), and 3.62 (1.76–7.48, Ptrend=0.004) for a BMI of 15–<18.5, 18.5–<25.0, 25–<30, and ≥30 kg/m2, and 1.61 (1.25–2.06) per 5 kg/m2 increment (n=130), and for early-onset ampulla of Vater cancer (n=19) was 1.00, 2.10 (0.75–5.88), and 5.45 (1.16–25.70, Ptrend=0.01), and 1.91 (1.10–3.32) per 5 kg/m2 increment. Higher BMI was not clearly associated with cancer-specific survival among ampulla of Vater cancer patients (HR 1.19, 95% CI: 0.89–1.61 for BMI ≥30 vs. 18.5–<25.0 kg/m2). Conclusions: Overall, the results show no clear association between higher BMI and ampulla of Vater cancer incidence or survival. However, strong positive associations were observed between BMI in young adulthood and risk of ampulla of Vater cancer and between BMI and early-onset diagnosis. Further studies are needed to verify these findings.

• Saeed, Usman; Myklebust, Tor Åge; Robsahm, Trude Eid; Aune, Dagfinn; Møller, Bjørn & Skålhegg, Bjørn Steen [Show all 8 contributors for this article] (2025). Associations between body mass index and gastroesophageal cancer incidence and mortality: novel insights from a nationwide registry-based cohort study. Diseases of the esophagus. ISSN 1120-8694. 38(2). doi: 10.1093/dote/doaf018. Full text in Research Archive Show summary

  The association between body mass index (BMI) and cancers of the esophagus and the stomach remains complex and requires further exploration. This study aimed to investigate this association, including early-onset (< 50 years) cancer and cancer related mortality. A nationwide registry-based cohort study was performed by linking data from multiple national registries in Norway. The cohort included 1,723,692 individuals, with 22,473 gastroesophageal cancer cases identified over 55,701,169 person-years of follow-up. In men, a 5 kg/m2 increase in BMI was associated with an increased risk of esophageal (HR 1.34, 95%CI 1.22–1.48) and cardia adenocarcinoma (HR 1.36, 95% CI, 1.22–1.50). This finding extended to individuals with high BMI in early life (16–29 years) for esophageal adenocarcinoma. The highest risk per 5 kg/m2 increase in BMI was observed for early-onset esophageal (HR 2.49, 95%CI 1.23–5.02) and cardia adenocarcinoma (HR 2.26, 95%CI 1.19–4.27). Among women, increased BMI was associated with a higher risk of both esophageal (HR 1.28, 95%CI 1.13–1.44) and gastric adenocarcinoma (HR 1.04, 95%CI 1.01–1.07). Women with elevated BMI in early life also demonstrated increased risk for these cancers. In both sexes, a 5 kg/m2 increase in BMI was inversely associated with squamous cell carcinoma of the esophagus. No association was observed between BMI and risk of cancer-related mortality. This study highlights an elevated risk of gastroesophageal adenocarcinomas with increasing BMI, with notable sex, age, and site-specific variations. The findings also point to a heightened risk of early-onset esophageal and cardia adenocarcinoma in men with high BMI.

• Aune, Dagfinn; Mala, Tom; Myklebust, Tor Åge; Nordsletten, Marie Wiborg; Robsahm, Trude Eid & Saeed, Usman [Show all 8 contributors for this article] (2024). The association between body mass index and vulvar and vaginal cancer incidence: findings from a large Norwegian cohort study | Cancer Causes & Control. Cancer Causes and Control. ISSN 0957-5243. 36(2), p. 191–198. doi: 10.1007/s10552-024-01930-z. Full text in Research Archive Show summary

  There is limited evidence of potential associations between body mass index (BMI) and risk of vulvar and vaginal cancer. We explored these associations in a large cohort of Norwegian women. The analytical dataset included 889,441 women aged 16–75&nbsp;years at baseline in 1963–1975. Multivariable Cox regression analyses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between BMI and vulvar and vaginal cancer incidence. During 30.1 million person-years of follow-up, 1748 incident vulvar and 408 incident vaginal cancer cases occurred. The HRs (95% CIs) for vulvar cancer for a BMI of 15- &lt; 18.5, 18.5- &lt; 25, 25- &lt; 30, 30- &lt; 35, ≥ 35 were 0.62 (0.38–1.01), 1.00 (reference), 1.23 (1.10–1.40), 1.43 (1.23–1.66) and 1.72 (1.35–2.20, ptrend &lt; 0.001), and per 5&nbsp;kg/m2 increment was 1.20 (1.13–1.26). The corresponding HRs (95% CIs) for vaginal cancer were 1.05 (0.52–2.15), 1.00, 0.89 (0.71–1.12), 0.95 (0.68–1.34), and 2.01 (1.29–3.13, ptrend &lt; 0.001), respectively, and per 5&nbsp;kg/m2 was 1.11 (0.99–1.25). The HR (95% CI) per 5&nbsp;kg/m2 increase in BMI at ages 16–29 was 1.28 (1.07–1.54, n = 250 cases) for vulvar and 1.53 (1.11–2.11, n = 66 cases) for vaginal cancers. The HR (95% CI) per 5&nbsp;kg/m2 for early-onset (&lt; 50&nbsp;years age at diagnosis) vulvar cancer was 0.92 (0.66–1.28, n = 87 cases) and 1.70 (1.05–2.76, n = 21 cases) for vaginal cancer. These results further support the associations between higher BMI and increased risk of vulvar and vaginal cancers, with suggestive stronger associations between BMI in early adulthood for both cancers and for early-onset vaginal cancer. Further studies are needed to elucidate these findings and investigate the underlying mechanisms.

• Saeed, Usman; Yakub, Sheraz; Barreto, Savio G.; Pandol, Stephen & Mala, Tom (2024). Reducing the risk of cancer with bariatric surgery: The need for evidence to guide practice. Scandinavian Journal of Surgery. ISSN 1457-4969. p. 263–335. doi: 10.1177/14574969241264064. Full text in Research Archive
• Aune, Dagfinn; Nordsletten, Marie Wiborg; Myklebust, Tor Åge; Robsahm, Trude Eid; Skålhegg, Bjørn Steen & Mala, Tom [Show all 8 contributors for this article] (2024). The association between body mass index and vulvar and vaginal cancer incidence: findings from a large Norwegian cohort study. Cancer Causes and Control. ISSN 0957-5243. 36, p. 191–198. doi: 10.1007/s10552-024-01930-z. Full text in Research Archive Show summary

  Background There is limited evidence of potential associations between body mass index (BMI) and risk of vulvar and vaginal cancer. We explored these associations in a large cohort of Norwegian women. Methods The analytical dataset included 889,441 women aged 16–75 years at baseline in 1963–1975. Multivariable Cox regression analyses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between BMI and vulvar and vaginal cancer incidence. Results During 30.1 million person-years of follow-up, 1748 incident vulvar and 408 incident vaginal cancer cases occurred. The HRs (95% CIs) for vulvar cancer for a BMI of 15- < 18.5, 18.5- < 25, 25- < 30, 30- < 35, ≥ 35 were 0.62 (0.38–1.01), 1.00 (reference), 1.23 (1.10–1.40), 1.43 (1.23–1.66) and 1.72 (1.35–2.20, ptrend < 0.001), and per 5 kg/m2 increment was 1.20 (1.13–1.26). The corresponding HRs (95% CIs) for vaginal cancer were 1.05 (0.52–2.15), 1.00, 0.89 (0.71–1.12), 0.95 (0.68–1.34), and 2.01 (1.29–3.13, ptrend < 0.001), respectively, and per 5 kg/m2 was 1.11 (0.99–1.25). The HR (95% CI) per 5 kg/m2 increase in BMI at ages 16–29 was 1.28 (1.07–1.54, n = 250 cases) for vulvar and 1.53 (1.11–2.11, n = 66 cases) for vaginal cancers. The HR (95% CI) per 5 kg/m2 for early-onset (< 50 years age at diagnosis) vulvar cancer was 0.92 (0.66–1.28, n = 87 cases) and 1.70 (1.05–2.76, n = 21 cases) for vaginal cancer. Conclusion These results further support the associations between higher BMI and increased risk of vulvar and vaginal cancers, with suggestive stronger associations between BMI in early adulthood for both cancers and for early-onset vaginal cancer. Further studies are needed to elucidate these findings and investigate the underlying mechanisms.

• Aune, Dagfinn; Nordsletten, Marie Wiborg; Myklebust, Tor Åge; Robsahm, Trude Eid; Skålhegg, Bjørn Steen & Mala, Tom [Show all 8 contributors for this article] (2024). Body mass index and penile cancer incidence: results from a Norwegian cohort study of 829,081 men. BMC Urology. 24(1), p. 1–6. doi: 10.1186/s12894-024-01636-z. Full text in Research Archive Show summary

  Background A few previous studies have suggested a possible association between adiposity and increased risk of penile cancer, however, the evidence is to date limited for this rare cancer. We investigated the association between body mass index (BMI) and penile cancer risk in a large Norwegian cohort. Methods The analyses included 829,081 men aged 16–75 years at baseline in 1963–1975. Multivariable Cox regression analyses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between BMI and penile cancer incidence. Results A total of 725 incident penile cancer cases occurred during 25.6 million person-years of follow-up. Compared to men with BMI 18.5-<25, the HRs (95% CIs) of those with a BMI of 15-<18.5, 25-<30, and ≥ 30 were 0.45 (0.15–1.41), 1.14 (0.97–1.33) and 1.63 (1.20–2.22), respectively, and the HR was 1.26 (1.12–1.42) per 5 kg/m2 increase in BMI. When the obese category was further subdivided in grade 1 (BMI 30-<35) and grade 2 obesity (≥ 35), the respe

• Saeed, Usman; Nordsletten, Marie Wiborg; Myklebust, Tor Åge; Robsahm, Trude Eid; Møller, Bjørn & Skålhegg, Bjørn Steen [Show all 8 contributors for this article] (2023). Cancer risk and survival according to body mass index in hepatobiliary malignancies: a nationwide registry-based cohort study. HPB. ISSN 1365-182X. 25(11), p. 1382–1392. doi: 10.1016/j.hpb.2023.07.882. Full text in Research Archive Show summary

  Background The aim of this study was to explore the associations between BMI and cancer of the liver, bile ducts, and gallbladder. Methods A registry-based cohort study was performed by linking data from several national registries in Norway. Results The cohort comprised 1 723 692 individuals including 4768 hepatobiliary cancer cases during 55 743 509 person-years of follow-up. In men, we found increased risk of cancer per 5 kg/m2 BMI increase for hepatocellular carcinoma and extrahepatic cholangiocarcinoma. In women there was increased risk of extrahepatic cholangiocarcinoma and gallbladder cancer. Women with high BMI in early adulthood had increased risk of intrahepatic cholangiocarcinoma. Reduced cancer-specific survival was found for all hepatobiliary malignancies in women with overweight and obesity. In men, reduced survival was observed in individuals with obesity for all hepatobiliary cancers, except gallbladder cancer. Increased risk of cancer-death per 5 kg/m2 BMI increase was found for hepatocellular carcinoma, intra-, and extrahepatic cholangiocarcinoma in women. For men, 5 kg/m2 BMI increase was positively associated with cancer-death from intrahepatic cholangiocarcinoma. Discussion This study supports the notion of an increased risk of hepatobiliary cancers with increasing BMI, with sex and age variations. The findings also suggest a higher risk of cancer-death with increasing BMI.

• Nordsletten, Marie Wiborg; Saeed, Usman; Myklebust, Tor Åge; Robsahm, Trude Eid; Møller, Bjørn & Skålhegg, Bjørn Steen [Show all 8 contributors for this article] (2023). Body mass index and its association with 22 cancer types: a Norwegian cohort study of 481 202 cancer cases. Acta Oncologica. ISSN 0284-186X. 62(10), p. 1273–1278. doi: 10.1080/0284186X.2023.2258443. Full text in Research Archive
• Saaed, Usman; Myklebust, Tor Åge; Robsahm, Trude Eid; Møller, Bjørn; Mala, Tom & Skålhegg, Bjørn Steen [Show all 7 contributors for this article] (2022). Body mass index and pancreatic adenocarcinoma: A nationwide registry-based cohort study. Scandinavian Journal of Surgery. ISSN 1457-4969. 112(1), p. 11–21. doi: 10.1177/14574969221127530. Full text in Research Archive Show summary

  Background and objective:An association between body mass index (BMI) and pancreatic cancer is suggested in observational studies. However, further studies are required to substantiate available evidence. The aim of this study was to explore the association between BMI and pancreatic ductal adenocarcinoma (PDAC) risk, treatment, and mortality. Methods:A registry-based cohort study was performed by combining data from four registries in Norway. Baseline data were collected between 1963 and 1975 with follow-up data collected until 2018. Kaplan–Meier curves and multivariable Cox regressions were estimated. Chi-square tests were used to analyze differences between groups. Results:The study cohort consisted of 1,723,692 individuals. A total of 8973 PDAC cases were identified during 55,744,749 person-years of follow-up. A 5 kg/m2 increase in BMI was associated with an increased risk of PDAC if high BMI at young age (16–29 years) (hazard ratio (HR): 1.21, 95% confidence interval (CI): 1.13–1.31), both for men (HR: 1.30, 95% CI: 1.15–1.46) and women (HR: 1.16, 95% CI: 1.05–1.28). In men, there was a 52% increase in risk of early-onset PDAC (<age 50) (HR: 1.52, 95% CI: 1.13-2.03) with 5 kg/m2 increase in BMI. A total of 2645 individuals were diagnosed with stage 1–3 disease, of whom 1131 underwent curative surgery. In all, 49% of normal weight, 38% overweight, and 30% obese individuals with stage 1–3 PDAC underwent surgery with curative intent (p < 0.001). Cancer survival was lower in overweight and obese individuals for both sexes. Analysis adjusted for sex, age, and period of diagnosis confirmed increased risk of cancer death in obese individuals. Conclusion:This study suggests that increased BMI in young adults may increase the risk of PDAC, and higher BMI in men is associated with an increased risk of early onset PDAC (<age 50). Overweight and obese individuals were less likely to undergo curative surgery and obese individuals had a higher risk of cancer-related death.

• Saaed, Usman; Myklebust, Tor Åge; Robsahm, Trude Eid; Kielland, Marlene Fritsch; Møller, Bjørn & Skålhegg, Bjørn Steen [Show all 8 contributors for this article] (2022). Risk and survival in colorectal cancer with increasing body mass index: A nationwide population-based cohort study. Colorectal Disease. ISSN 1462-8910. p. 1–11. doi: 10.1111/codi.16367. Full text in Research Archive Show summary

  Aim: The aim was to explore potential associations between the body mass index (BMI) and the risk of colorectal cancer (CRC), including subsites of the colon, and cancer-specific death. Methods: A registry-based cohort study was conducted with baseline data gathered from the Norwegian Tuberculosis Screening Programme, collected between 1963 and 1975, and linked to follow-up data from the Cancer Registry of Norway and the Norwegian Cause of Death Registry. Cox regression models were used to explore associations between BMI and CRC risk and cancer-specific death. Results: Of 1 723 692 included individuals, 76 616 developed CRC during 55 370 707 person-years of follow-up. In men, a 5 kg/m2 increase in BMI was associated with an increased risk of colon cancer, including both right and left subsites, and rectal cancer. Allowing for nonlinearities, we found a U-shaped association for the right colon and an inverse U-shape for the left colon and rectum cancer. In women, a 5 kg/m2 increase in BMI in early adulthood was associated with increased risk of colon cancer, including both subsites. In women, an increased risk of CRC death with increasing BMI was found for colon cancer. Conclusions: Men of all ages have an increased risk of CRC with increasing BMI, with the highest risk for right-sided colon cancer. An increased risk for colon cancer was also found in women with high BMI in early adulthood. Furthermore, women of all age groups appeared to have an increased risk of CRC death with higher BMI.

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• Saeed, Usman; Saunes, Therese Karina; Sjo, Ole Helmer & Schultz, Johannes Kurt (2025). Giant Colonic Diverticulum: Case report of a rare complication of a common disease. International Journal of Surgery Case Reports (IJSCR). 127, p. 1–6. doi: 10.1016/j.ijscr.2025.110909. Full text in Research Archive Show summary

  Introduction and importance: Giant Colonic Diverticulum (GCD) is a rare but potentially life-threatening complication of diverticular disease, defined as a diverticulum larger than 4 cm, most commonly arising in the sigmoid colon. Its rarity could lead to diagnostic delays and mismanagement. Case presentation: A 64-year-old Caucasian female presented with persistent abdominal pain and abdominal swelling. Examination revealed a palpable mass in the left flank. A computed tomography (CT) scan demonstrated an 11x10x14 cm air-filled cavity adjacent to the sigmoid colon, initially misdiagnosed as contained perforated diverticulitis. Following a literature review, the diagnosis of GCD was considered. Definitive treatment involved a segmental sigmoid colectomy with en-bloc resection of the diverticulum. The postoperative course was uneventful, and the patient was discharged on postoperative day four with complete symptom resolution. Clinical discussion: The presentation of GCD can mimic common complications of diverticular disease, making diagnosis challenging. CT imaging is critical, typically showing a large air-filled cavity connected to the colon. Surgical resection is the treatment of choice to prevent serious complications such as perforation, abscess, volvulus, or malignancy. In this case, en-bloc resection proved effective, highlighting the importance of prompt surgical management. Conclusion: GCD is a rare and under-recognized clinical entity. Increased awareness is essential to ensure timely diagnosis and treatment. This case underscores the importance of integrating imaging findings, clinical judgment, and surgical intervention for optimal outcomes and emphasizes the need for further case documentation to aid in management strategies.

• Mala, Tom; Yakub, Sheraz & Saeed, Usman (2023). Redusert kreftrisiko etter fedmekirurgi. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 143(13). doi: 10.4045/tidsskr.23.0501. Full text in Research Archive

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