Cancer is the second leading cause of death worldwide and accounted for 9.6 million deaths in 2018 (WHO, 2018). Globally, the most prevalent cancers are lung, breast, colorectal, prostate, skin, and stomach cancer (National Cancer Institute, 2020). In Saudi Arabia, 24,485 new cases of cancer were detected in 2018 across all age groups and both sexes, including breast, colorectal, and thyroid cancer, leukemia, and non-Hodgkin's lymphoma; these were also the top five cancers leading to mortality (International Agency for Research on Cancer, 2018). Despite the small number of cancer cases in Saudi Arabia compared with the rest of the world, the number of cases is expected to increase each year due to radical lifestyle changes and the Saudi population's expected growth (Althubiti and Eldein, 2018). Therefore, understanding factors leading to cancer and warning symptoms of cancer could encourage individuals to pay more attention to their health concerns.The National Cancer Institute (2015) reported risk factors of cancer including age, heredity, exposure to chemical substances, and ionizing or ultraviolet radiation.

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Background: Vitamin D deficiency is a worldwide concern. The aim of the current study was to determine the vitamin D level and its contributing factors in Sudanese women. Methods: In this cross-sectional study, 251 Sudanese women attending Family Health Centers in Khartoum, Sudan were interviewed. Following the exclusion of confounding factors, samples from 190 women were analzsed. Serum 25 hydroxyvitamin D “25(OH) D” was quantified using competitive electrochemiluminescence immunoassay. Results: Participants’ age ranged from 18 to 85 years with a mean age (±SD) of 40.2 (±14.06) years. The mean (±SD) vitamin D level was 13.4 (±6.72) ng/ml, ranged 3.00–36.5 ng/ml and the median was 12.7 ng/mL. In total, 157 out of 190 (82.6%) had vitamin D serum levels below 20 ng/ml (deficient); of whom, 52 (27.4%) were in the age group 21–30 years ( P value = 0.228). The correlation between vitamin D level and residence outside Khartoum, sun-exposed face and hands, and face and limbs in comparison with being completely covered were found to be statistically significant ( p values 0.008, 0.023, and 0.036). Conclusion: This study displayed a high percentage (82.6%.) of vitamin D deficiency among women in Sudan, and this in part may indicate that sunshine alone cannot guarantee vitamin D sufficiency in the tropics. Family physicians in tropical countries should screen those with clinical presentations related to vitamin D deficiency.

Background: The role of vitamin D in the development, progression, and prognosis of breast cancer, though widely studied worldwide, has been inconclusive. This study intended to assess the role of some factors (including serum vitamin D level, sun-exposed area, dietary factors, and physical activity) as predictors of the development of invasive breast cancer (IBC) among Sudanese women. Methods: A case–control study was conducted on 200 Sudanese women (100 with newly diagnosed IBC and 100 matched healthy females). Serum 25-hydroxyvitamin D was measured through a competitive electrochemiluminescence immunoassay. Matching analysis was adopted by R version 3.4.1 making use of the “MatchIt” package for calculating propensity scores to build a confounder-adjusted, multiple generalized, linear logistic regression model. Results: Participants’ age ranged from 28 to 85 years with a mean [±standard deviation (SD)] of 48.10 (±12.11) years. The mean (±SD) serum vitamin D level was 12.97 (±8.60) and 13.79 (±6.79) ng/mL in breast cancer and noncancer Sudanese women, respectively [P = 0.013; odds ratio (OR) 0.862; 95% confidence interval (CI) 0.766–0.969; β = 0.149)]. Sun-exposed area ( P = 0.038; OR 0.013; 95% CI 0.000–0.782; β = 4.339) is significantly and negatively associated with breast cancer development. While moderate physical activity ( P = 0.0008; OR 2625.430; 95% CI 26.647–258673.001; β = 7.873) is significantly and positively associated with IBC risk. Occasional consumption of milk, dairy products, eggs, and fish reduces the risk of developing IBC by 78.1%, 75.0%, 78.4%, and 76.4%, respectively. Conclusion: The higher the plasma vitamin D level by one unit, the lower the risk of breast cancer by 13.84%. Sedentary lifestyle, reduced sun-exposed skin area, and low serum vitamin D levels can be considered as predictors of IBC. Encouraging moderate physical activity and consumption of certain foods may, in part, decrease the precipitating risks of breast cancer. More studies and research are needed to confirm these findings.

This article is based on the author's S.J.D. thesis.Improving the resolution of international tax disputes has witnessed recent developments. The Organization of Economic Development and Cooperation (“OECD”) amended its Model Convention and Commentary to include mandatory and binding arbitration of tax disputes between two treaty countries that have been unsuccessful in resolving the disputes through negotiations between their tax authorities. The United States has amended its income tax treaties with Belgium, Canada, Germany and France to include mandatory and binding arbitration of unresolved tax disputes. These amendments are undoubtedly an important step toward improving the resolution of international tax disputes. Nevertheless, the Article argues that these amendments fail to achieve this goal. By their terms, the amendments enable countries to avoid the arbitration. There is a risk these amendments will damage previously existing resolution methods that have generally been successful. The arbitration, as currently proposed, can be used by taxpayers to achieve abusive and undesirable tax results. The Article argues that these amendments will not serve the two primary goals income tax treaties aim at achieving which are preventing double taxation as well as double nontaxation (i.e., escaping taxation).In Part one of the Article I present a brief overview of major contributions to the literature in this field. I set forth an evaluation methodology that focuses on two questions: First, does a mandatory arbitration provision fit in the overall network of tax treaties? Second, can the mandatory and binding arbitration provision actually resolve disputes? I argue that when we are able to answer positively to both questions, a recommendation to adopt such a provision will follow.In Part two I focus on the OECD proposal for mandatory and binding arbitration aimed at improving the resolution of international tax disputes. I conclude that under the current proposed structure, a negative answer to the above evaluation questions is more likely to be given than a positive one. I address certain policy issues related to the proposal, structural deficiencies embodied in it as well as possible negative consequences it may have. I conclude that the proposal should be reexamined.In Part three I examine the mandatory and binding arbitration provisions that were adopted recently in a few income tax treaties to which the United States is partner. I conclude that the United States expresses a position aimed at limiting the application of mandatory and binding arbitration.Part four is a summary of the work. I explain that I generally do not oppose the adoption of mandatory and binding arbitration. Nevertheless, I offer some considerations regarding the circumstances accompanying the application of the proposed provisions as well as their structure. I suggest that the proposals should be reexamined because they lack features that are major and crucial for successful mandatory and binding arbitration and because of the risk that they will negatively affect pre-existing dispute resolution mechanisms.