<![CDATA[Radiotherapy (RT) is integral to cancer care but frequently damages skin and mucosal barriers, predisposing patients to infection. This systematic review examined whether water, sanitation, and hygiene (WASH) practices influence skin and mucosal infections in adults receiving RT, with emphasis on low- and middle-income countries (LMICs). We searched PubMed, Embase, Scopus, CINAHL, and the Cochrane Library from inception using controlled terms and keywords for RT, WASH, and infection; two reviewers screened records and appraised quality (Cochrane RoB, ROBINS-I). Twelve studies met inclusion: two randomized trials of washing vs. no washing during breast RT (n?198), one pediatric RCT of topical honey for oral care, two oncology cohorts describing pathogens and risk, and seven LMIC studies adapted to RT contexts evaluating facility or household WASH. Washing reduced moist desquamation and grade ?2 skin toxicity; honey decreased severe mucositis, microbial colonization, and length of stay. Severe radiodermatitis strongly predicted culture-confirmed infection (OR?5.9), with Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa most common. Facility WASH programs improved hand hygiene/compliance, and household WASH deficits were associated with higher infectious risk, though RT specific endpoints were limited. Conclusion: Low-cost, WASH-aligned hygiene bundles permissive skin washing, structured oral care, and basic facility/household WASH supports are biologically plausible, feasible in LMICs, and should accompany RT while RT specific LMIC trials with infection endpoints are prioritized.]]>
