Purpose: Pain is a multifactorial and subjective experience. Psychological and social factors can modulate it. This study analyzed whether and how prolonged cancer pain is related to the social-relational environment's characteristics. Specifically, we investigated whether the caregiver's emotional support, his/her compassion ability or, on the contrary, his/her personal distress, associates with the patient's pain level. Methods: The sample consisted of 38 cancer patients suffering from pain and 38 family caregivers. The patients completed the McGill Pain Questionnaire (MPQ), the Balanced Emotional Empathy Scale (BEES) referred to caregiver, and an interview concerning the patient's perception of the caregiver's compassion level. Caregivers completed the distress thermometer (DT), the BEES, and an interview assessment of their compassion level. Results: Caregiver's distress level correlated with patient's pain intensity (r = .389; p = .028). Exploratory linear regression confirmed this association (R2 = .151; F (1, 30) = 5.33; p = .028; β = 0.389). The number of problems reported by caregivers correlated with the patients' pain level (r = .375; p = .020), which was verified in a regression analysis (R2 = .140; F (1, 36) = 5.88; p = .020; β = 0.375). In particular, the caregiver's amount of emotional problems was related to patient's pain level (r = .427; p = .007); this result was reaffirmed in a regression (R2 = .182; F (1, 36) = 8.03; p = .007; β = 0.427). Conclusions: Our results show an association between social suffering, as indicated by the caregiver's emotional distress and the patient's physical pain. The results also highlight high distress levels and emotional problems among caregivers. The work emphasizes the need of a bio-psychosocial approach in managing cancer pain, along with the necessity to find effective interventions to fight emotional distress in family caregivers. The recovery of the caregivers' emotional resources could have beneficial implications on the patients' pain.