Background: Communication in oncology practice presents numerous challenges. Patients may react to the diagnosis and treatment information with unpredictable and difficult to manage emotions, which may distress clinicians and affect patient-physician relationships. An effective communication has shown a beneficial effect on satisfaction from both patients and providers, as well as on quality of health care provision and patients’ adherence, decision-making processes and outcomes. Aim: To identify the most important and hardest topics to discuss during consultation that pose a challenge for Mexican medical oncologists during their clinical practice. Methods: Physicians were reached out by a messaging platform to complete a survey that addressed the most relevant and difficult issues for discussion and the frequent challenges they face during information exchange. Results: A total of 115 oncologists completed the survey. Most of them identified treatment objectives, prognosis and treatment selection as important issues to discuss with patients. They coincided that the hardest matters to disclose were palliative care referral, treatment objectives, prognosis and recurrence. Also, oncologists reported that the most important challenges they face when communicating with patients are being honest without being hopeless (43%) and responding to patients’ emotions (21%). 92% expressed that they would like to receive formal training in communication skills. Conclusions: The issues regarded as highly important to discuss with patients were also the most difficult ones to address, possibly due to barriers related to patients’ emotional reactions when receiving bad news. The incorporation of a psychologist could promote calmness and trust, aid in information assimilation, and provide support to partners and relatives, as needed. Also, results showed the interest of oncologists in receiving formal training in communication skills, which reinforces the need to include this training as part of the medical oncology curriculum to ease transmission and comprehension of information.