IMPORTANCE Understanding the challenges faced by an increasing number of cancer survivors can guide the development and implementation of effective survivorship care models. OBJECTIVE To identify the physical, emotional, and practical concerns and associated unmet needs reported by cancer survivors. DESIGN, SETTING, AND PARTICIPANTS This cross-sectional survey study obtained data from the Experiences of Cancer Patients in Transitions Study of the Canadian Partnership Against Cancer, in collaboration with cancer agencies in the 10 Canadian provinces, that was disseminated in 2016. This analysis included only adult survivors aged 30 years or older who underwent chemotherapy, radiation therapy, surgical treatment, or a combination of these therapies for breast, prostate, colorectal, melanoma, or hematological cancer within the past 1 to 3 years. Data synthesis and quality assessment were conducted in 2017. Data analysis was completed in July 2019. MAIN OUTCOMES AND MEASURES The outcomes were the (1) quantification of the magnitude and multiplicity of the physical, emotional, and practical concerns of adult survivors of breast, colorectal, prostate, melanoma, or hematological cancer; (2) exploration of the magnitude of associated unmet needs; and (3) identification of patient-, treatment-, and cancer-specific factors associated with the reporting of unmet needs. RESULTS Overall, 10 717 adult respondents were included (5660 [53%] female and 6367 [60%] aged Ն65 years). The median number of concerns per respondent was 6 (interquartile range [IQR], 3-10). Among respondents with concerns, help was sought for a median of 2 (IQR, 0-4) concerns. Unmet needs were reported for a median of 4 (IQR, 2-7) concerns. Emotional concerns were reported by 8330 respondents (78%), physical concerns by 9236 respondents (86%), and practical concerns by 4668 respondents (44%). At least 1 unmet need was reported by 7033 survivors (84%) with emotional concerns, 7475 (81%) with physical concerns, and 3459 (74%) with practical concerns. Age, sex, annual income, marital status, geographic location, language, and treatment type