Distress during SARS-CoV-2 outbreak affected also cancer patients' well-being. Aim of this study was to investigate patient' reactions and behavior (flexible-adaptive vs. inflexible-maladaptive) during the SARS-CoV-2 outbreak. A cross-sectional survey was designed with a self-report questionnaire, "the ImpACT questionnaire," developed for the study. Regression analysis was performed on data. Four hundred and forty five cancer patients from 17 Italian regions participated in the study. 79.8% of participants were female (mean age of 58 years). 92.6% of participants reported feeling vulnerable to COVID-19 contagion; 75.6% reported helpless, 62.7% sad, 60.4% anxious, and 52.0% anger. Avoidance of thinking about coronavirus is the principal maladaptive behavior that emerged. Participants who reported feeling anxious were more likely to have fear of staff being infected with COVID-19 (OR = 3.01; 95% CI = 1.49-6.30) and to have disrupted sleep due to worry (OR = 2.42; 95% CI = 1.23-4.83). Younger participants reported more anxiety (OR = 0.97; 95% CI = 0.94-1.00); men reported feeling calm more than women (OR = 2.60; 95% CI = 1.27-5.43). Majority of cancer patients reported serious concerns regarding SARS-CoV-2 infection; reliable information and psychological support must be offers to respond to these needs.