Administration of effective anticancer treatments should continue during pandemics. However, the outcomes of curative and palliative anticancer treatments during the coronavirus disease (COVID-19) pandemic remain unclear. The present retrospective observational study aimed to determine the 30-day mortality and morbidity of curative and palliative anticancer treatments during the COVID-19 pandemic. Between March 1 and June 30, 2020, all adults (n=2,504) with solid and hematological malignancies irrespective of cancer stage and type of anticancer treatments at five large comprehensive cancer centers in Saudi Arabia were included. The 30-day mortality was 5.1% (n=127) for all patients receiving anticancer treatment, 1.8% (n=24) for curative intent, 8.6% (n=103) for palliative intent and 13.4% (n=12) for COVID-19 cases. The 30-day morbidity was 28.2% (n=705) for all patients, 17.9% (n=234) for curative intent, 39.3% (n=470) for palliative intent and 75% (n=77) for COVID-19 cases. The 30-day mortality was significantly increased with male sex [odds ratio (OR), 2.011; 95% confidence interval (CI), 1.141-3.546; P=0.016], body mass index (BMI) <25 (OR, 1.997; 95% CI, 1.292-3.087; P=0.002), hormone therapy (OR, 6.315; 95% CI, 0.074-2.068; P=0.001) and number of cycles (OR, 2.110; 95% CI, 0.830-0.948; P=0.001), but decreased with Eastern Cooperative Oncology Group performance status (ECOG-PS) of 0-1 (OR, 0.157; 95% CI, 0.098-0.256; P=0.001), stage I-II cancer (OR, 0.254; 95% CI, 0.069-0.934; P=0.039) and curative intent (OR, 0.217; 95% CI, 0.106-0.443; P=0.001). Furthermore, the 30-day morbidity significantly increased with age >65 years (OR, 1.420; 95% CI, 1.075-1.877; P=0.014), BMI <25 (OR, 1.484; 95% CI, 1.194-1.845; P=0.001), chemotherapy (OR, 1.397; 95% CI, 1.089-5.438; P=0.032), hormone therapy (OR, 1.527; 95% CI, 0.211-1.322; P=0.038) and immunotherapy (OR, 1.859; 95% CI, 0.648-4.287; P=0.038), but decreased with ECOG-PS of 0-1 (OR, 0.502; 95% CI, 0.399-0.632; P=0.001), breast cancer (OR, 0.569; 95% CI, 0.387-0.836; P=0.004) and curative intent (OR, 0.410; 95% CI, 0.296-0.586; P=0.001). The mortality risk was lowest with curative treatments. Therefore, such treatments should not be delayed. The morbidity risk doubled with palliative treatments and was highest among COVID-19 cases. Mortality appeared to be driven by male sex, BMI <25, hormonal therapy and number of cycles, while morbidity increased with age >65 years, BMI <25, chemotherapy, hormonal therapy and immunotherapy. Therefore, oncologists should select the most effective anticancer treatments based on the aforementioned factors.