Influence of time between surgery and adjuvant radiotherapy on prognosis for patients with head and neck squamous cell carcinoma: A systematic review

The timing of postoperative radiotherapy following surgical intervention in patients with head and neck cancer remains a controversial issue. This review aims to summarize findings from available studies to investigate the influence of time delays between surgery and postoperative radiotherapy on clinical outcomes. Articles between 1 January 1995 and 1 February 2022 were sourced from PubMed, Web of Science, and ScienceDirect. Twenty-three articles met the study criteria and were included; ten studies showed that delaying postoperative radiotherapy might negatively impact patients and lead to a poorer prognosis. Delaying the start time of radiotherapy, 4 weeks after surgery did not result in poorer prognoses for patients with head and neck cancer, although delays beyond 6 weeks might worsen patients' overall survival, recurrence-free survival, and locoregional control. Prioritization of treatment plans to optimize the timing of postoperative radiotherapy regimes is recommended.

Radiotherapy scheduling using prime numbers

Background

The optimal delivery of radiation therapy to achieve maximum tumour cell kill while limiting damage to normal tissues underlies any radiation therapy treatment protocol. The biological effectiveness of radiation therapy is closely related to cellular reproductive activity. The scheduling of dose fraction to a time where actively dividing cells are at their most radiosensitive stage (RS) has potential to enhance therapeutic efficacy.

Materials and methods

A prime number is a natural number >1 whose only divisors are 1 and the number itself.

Purpose

We propose that the use of prime numbers in the scheduling of radiotherapy treatments could maximise biological effectiveness by facilitating the irradiation of the greatest number of cells at their most RS stage, and ultimately improve the therapeutic ratio of radiation therapy.

Conclusions

The theoretical clinical implementation of this concept into the scheduling of radiation therapy is discussed.