Objective The aim of this study was to investigate the association between cancer patients' ability to share information about their illness with their social network and attachment style dimensions, alexithymia, and quality of life. We hypothesised that ability to share information about one's cancer with family, friends, and medical teams would be positively associated with quality of life and secure attachment and negatively associated with alexithymia. Methods Forty‐five cancer patients were recruited from the Psycho‐oncology Unit of the San Camillo‐Forlanini Hospital in Rome. We collected anamnestic data and self‐report data on social sharing ability, quality of life, alexithymia, and attachment. Results Sharing with family (B = 4.66; SE = 1.82; β = .52; SE = 0.20; t(41) = 2.6; P = .0143) was the only predictor of global health status, and attachment security was the only predictor of mean social sharing (B = 0.25; SE = 0.06; β = .63; SE = 0.14; t(41) = 4.4; P < .0001). Conclusions Encouraging patients to share information about their experience of cancer may help to improve their quality of life. Attachment security seems to promote social sharing. Psychological assessments of cancer patients should cover both ability to share information about one's cancer with family and attachment security.