Background: The incidence of cancer is increasing in developing countries. Diet and cancer have a close relationship. Objectives: The objectives of this study were to measure the cancer prevention-related nutrition knowledge, attitudes, and practice and barriers related to healthy food in a low income community, and to assess their cancer worries. Subjects and Methods: This cross-section descriptive study was carried out in a slum area in Cairo on a convenience sample of 414 adults permanently residing in the area. A structured interview questionnaire was used for collecting participants' socio-demographic data, knowledge about cancer, attitude and practice towards cancer dietary prevention, cancer worry scale, and the barriers preventing eating healthy food. Results: The study revealed a wide range of participants' knowledge scores. Participants' attitude towards a healthy diet was also low. The most deficient practices were related to the intake of balanced diet and vitamins, practice of exercise, and cancer screening. The most frequent barrier to a healthy diet was taste (42%), while the lack of information was the least (3.1%). Multivariate analysis showed that the knowledge score was positively predicted by cancer worry score. The attitude score was positively predicted by age and knowledge score, and the practice score by married status, crowding index, and attitude score. Conclusion: there is a poor level of knowledge and inadequate practices regarding cancer dietary prevention despite good attitudes, in addition to high worries about cancer. Implications for Practice: There is urgent need for awareness raising intervention programs for dietary prevention of cancer.