Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 10 1 2018 04 18 3 11 EN Farzad Maleki Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Hamideh Rashidian Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Bahareh Sasanfar Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Azam Majidi Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Toorang Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Azin Nahvijou Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Homaei Shandiz Cancer Research Center, Mashahd University of Medical Sciences, Mashahd, Iran Ghasem Janbabaei Gastrointestinal Cancer Research Center, Imam Khomeini Hospital, Mazandaran University of Medical Sciences, Sari, Iran Samaneh Borhani Gastrointestinal Cancer Research Center, Imam Khomeini Hospital, Mazandaran University of Medical Sciences, Sari, Iran Gholamreza Roshandel Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran Zahra Sedaghat Department of Public Health, School of Public Health, Bushehr University of Medical Science, Bushehr, Iran. Maryam Marzban Department of Public Health, School of Public Health, Bushehr University of Medical Science, Bushehr, Iran. Ali Ghanbari Motalgh Gastrointestinal Cancer Research Center, Imam Khomeini Hospital, Mazandaran University of Medical Sciences, Sari, Iran Davood Mohammadzadeh Partoo Radiotherapy Oncology Center, Urmia, Iran Ali Kazemian Radiotherapy Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Mohammad Ali Mohagheghi Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran Kazem Zendehdel Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran AND Cancer Biology Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran 2018 02 19 2018 04 07 Background: Muslim cancer patients and healthcare professionals face several challenges about the necessity of fasting and its possible side effects during the holy month of Ramadan. We aimed to study the prevalence of fasting among cancer patients during Ramadan and opinions of health care professionals about fasting among cancer patients in Iran.  Methods: We conducted a cross-sectional survey during the Ramadan (July-August) in 2013. Participants were 620 cancer patients and, 187 healthcare professionals in several cancer clinics from different provinces of Iran. We used self-administered questionnaires and collected data from patients, and healthcare professionals to collect data. We performed descriptive analysis by using Stata statistical software.  Results: Out of 620 patients who participated in this study, 428 (69%) were women. 76 (13%) of patients had fasted for at least a day during Ramadan and, from which 41 (7%) had fasted whole months because of their religious belief. Among patients who had refrained from fasting, the reasons were lack of sufficient physical strength (403, 65%), excessive thirst (141, 23%). 275 (44%) of participants had consulted with their physician about fasting. We found that more than 50% of physicians advised against fasting for patients following surgery, pre-operation, recent hospitalization, and consumption of oral or intravenous chemotherapy. Most of the healthcare professionals (68%) believed that cancer survivors could not fast even if they have no signs or symptoms or side-effects after the treatment. Conclusion: Although most of the cancer patients refrain from fasting, some cancer patients practice fasting and face challenges during the holy month of Ramadan in Iran. Most patients consult about fasting in Ramadan with their doctor who has variable opinions about this issue. Development of guidelines for healthcare professional and cancer patients regarding Ramadan fasting is needed.   https://bccr.tums.ac.ir/index.php/bccrj/article/view/248 https://bccr.tums.ac.ir/index.php/bccrj/article/download/248/02