Introduction: An inadequate diet and nutritional deterioration influence the progression and prognosis of cancer patients. However, limited data exists on the dietary patterns of oncology patients in Latin America. Objectives: To describe the dietary patterns and nutritional status of cancer patients upon hospital admission to a specialized oncology center in Latin America. Methods: An exploratory cross-sectional study including 332 patients with solid and hematologic tumors. Dietary and nutritional assessments were conducted using standardized tools, clinical records, and dietary surveys. The analysis included fruit, vegetables, fiber, saturated fat, and simple sugar intake, along with nutritional status indicators. Missing dietary data were categorized as “Data not available” to ensure transparency. Results: Low consumption of fruits (38-40%), vegetables (10-13%), and fiber (59-71%) were observed, alongside a high intake of saturated fats and simple sugars. Among patients with solid tumors, 13.7% consumed more than 350 grams of saturated fats per week, compared to 25.6% of those with hematologic tumors. Additionally, 14.2% of solid tumor patients and 28.9% of hematologic tumor patients reported consuming over 25 grams of simple sugars daily. These dietary patterns are associated with chronic inflammation, oxidative stress, and an increased risk of tumor progression. Conclusions: Cancer patients exhibited poor dietary patterns and nutritional risk factors that may negatively impact clinical outcomes. These findings underscore the need for culturally adapted nutritional strategies, integrated into oncology treatment and led by multidisciplinary teams, to optimize nutritional status and clinical outcomes.