Making Up for Missed Radiotherapy Sessions: How We Keep Your Treatment on Track

In Radiation Oncology, every treatment session is part of a carefully planned sequence designed to destroy cancer cells while allowing healthy tissues to recover. When a session is missed—because of illness, equipment issues, or personal reasons—the total treatment time can be extended, which may reduce the overall effectiveness of therapy.

In a landmark study published in Clinical Oncology, Dr. R. G. Dale and colleagues from the U.K. described practical ways to compensate for missed radiotherapy days, particularly in head and neck cancers. These tumors tend to regrow quickly, and research shows that each day of delay can reduce local tumor control by 1–2%.

To minimize this loss, radiation oncologists use radiobiological models—specifically, the linear-quadratic model and the concept of biologically effective dose (BED)—to adjust the total dose or fractionation schedule. Depending on the case, compensation may involve adding weekend sessions, scheduling two treatments a day (at least six hours apart), or slightly increasing the dose per fraction, always with caution to protect normal tissues.

The key message from the study is that the problem is not the missed day itself but the total extension of the treatment. Longer overall treatment times give cancer cells a chance to repopulate, making therapy less effective. In Costa Rica, where radiotherapy centers often serve patients traveling long distances, anticipating possible interruptions—such as public holidays or machine maintenance—is essential for maintaining continuity.

For patients, the best way to support their treatment is to attend every scheduled session and immediately report any obstacle that might cause a delay. The care team can adapt the plan, but communication and collaboration are vital.

Simply put, every radiotherapy session matters. Each treatment fraction contributes to curing the disease, and keeping the schedule intact ensures that the radiation works exactly as intended. By staying consistent and informed, patients and their oncology team can work together to achieve the best possible outcome.