Peritoneal carcinomatosis is a severe disease progression in patients with intra-abdominal cancer, and it remains one of the most common causes of incurability in these cases. An aggressive strategy with cytoreductive surgery (CCR) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a therapeutic schedule focused on the local handling of this progression, with many studies showing a significant increase in the median overall survival compared to the systemic chemotherapy treatment. Examples of drugs used in this type of administration are oxaliplatin, carboplatin, cisplatin, mitomycin C, irinotecan, paclitaxel, docetaxel, doxorubicin and melphalan. Given that this protocol is a local treatment, with no systemic effect intention, and based on the premise that the same concentration produces a similar effect and toxicity, doses should be considered in terms of concentration instead of being defined by the body surface area (BSA). It should be kept in mind that, in HIPEC, the drug does not need to be distributed in order to reach the biophase (peritoneal cavity) and, therefore, homogenous concentrations should be achieved in the instillation solution. However, in the reviewed literature, the doses in HIPEC were defined by the BSA. In some of the studies, the method for calculating the volume of instillation was not specified. Therefore, the volume may vary depending on the capacity of the abdominal cavity to hold liquid or may be fixed for all patients [1]. Consequently, the initial drug concentration is no longer constant, and it depends on the volume of the instilled solution.