Impact of COVID-19 on Advanced Cancer Patients' Pain Care: Warning About Chloroquine and Hydroxychloroquine.

Dear Editor,

In recent few months, the world has experienced a new and unique situation with the spreading of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (1, 2). Signs and symptoms include fever, sore throat, cough, fatigue, headache, nausea, vomiting, diarrhea, and shortness of breath (3). Close contact with infected people and touching contaminated surfaces are the most important ways of coronavirus spreading (4). Old age is known as a risk factor for poor prognosis of COVID-19 and ICU admission. Old age is not only a major risk factor for COVID-19 infection but also a risk factor for many cancers (5, 6). Cancer patients receive diverse palliative care medications, especially for the control of pain, some of which such as methadone can prolong QTc interval (7). The QTc interval prolongation can be seen in up to 20% of patients. However, its clinical importance is not so significant (8, 9). Many protocols are described for the treatment of COVID-19 (10). Two of the most prevalent drugs used for COVID-19 treatment are chloroquine and hydroxychloroquine (11-13). Chloroquine and hydroxychloroquine can be associated with electrocardiographic QT interval prolongation. The QT interval prolongation is a risk predictor of developing potentially lethal Torsade de Pointes dysrhythmia (14). Since old age is a risk factor for both cancer and COVID-19, it is important to pay special attention to fatal drug interactions in elderly cancer patients with SARS-CoV-2 infection. From this point of view, in any patient with cancer or non-cancer chronic pain, even a young person who is infected with SARS-CoV-2 at the same time, it should be noted that drug interactions do not affect his/her outcome.