Whether 14 days or 21 days of chemotherapy is better depends on the specific situation. Some chemotherapy regimens specify 14 days/cycle, while others specify 21 days/cycle. If a 14-day/cycle chemotherapy regimen is delayed to 21-day chemotherapy for no reason, the anti-tumor efficacy will definitely be reduced. If the 21-day chemotherapy is given 1 week earlier, it is possible that the effect will be good, but it may also bring more adverse effects to the patient, such as causing more serious bone marrow suppression.