When should radiation therapy be initiated for head and neck cancer?

When to Start Radiation Therapy in Head and Neck Cancer

Radiation therapy for head and neck cancer should be initiated within 6 weeks of surgery for postoperative cases, and without delay for definitive treatment, as delays beyond 6 weeks are associated with decreased survival. 1

Postoperative Radiation Therapy Timing

Standard Timing Guidelines

• Initiate PORT within 6 weeks of surgery as recommended by NCCN guidelines, as delays beyond this timeframe are associated with decreased overall survival (adjusted HR 1.13) 1
• The optimal window is 5-6 weeks postoperatively, with no survival benefit demonstrated for starting earlier than 4 weeks 1
• Progressive survival decrements occur with increasing delays beyond 7 weeks (HR 1.09 for 7-8 weeks, 1.10 for 8-10 weeks, and 1.12 for >10 weeks) 1
• Keep total time from surgery to completion of radiotherapy as short as possible, ideally less than 6 weeks for patients with high-risk features 2, 3

Critical Exception: Dental Extractions

• Dental extractions should occur at least 2 weeks before starting radiation therapy to allow adequate healing 4
• However, in rapidly progressing tumors, extractions should be deferred and not cause delay in radiation therapy initiation, as oncologic control takes priority 4
• A 2-week healing period is advised only when this does not compromise oncologic control 4

Definitive Radiation Therapy Timing

Early Stage Disease

For early T1-T2 N0 oral cancer:

• Surgery should not be delayed beyond 8 weeks from diagnosis (95% consensus) 4
• If surgery cannot occur within 8 weeks, immediate radiotherapy should be considered rather than continued monitoring 4

For early T1 N0 laryngeal cancer:

• If surgery delay of 4-8 weeks is anticipated, radiotherapy should be recommended immediately instead of surgery (67.5% agreement) 4
• If delay exceeds 8 weeks, radiotherapy should be strongly recommended immediately over surgery (92.5% agreement) 4

Advanced Stage Disease

For advanced head and neck cancer (T4 N1 laryngeal, N2b oral, requiring bone resection):

• Surgery should not be delayed beyond 4 weeks of diagnosis (87.5% strong agreement) 4
• If surgery cannot occur within 4 weeks, alternative treatment such as radiotherapy or chemoradiotherapy should be given immediately (90% strong agreement) 4

Concurrent Chemoradiation Timing Considerations

Sequencing of Chemotherapy and Radiation

• Starting chemotherapy before radiation therapy improves locoregional control (3-year LRC 90.9% vs 78.2%, HR 0.33) 5
• This sequencing advantage applies to locoregional control but does not impact distant control, progression-free survival, or overall survival 5
• The standard regimen is cisplatin 100 mg/m² every 3 weeks with conventional fractionation RT (2.0 Gy per fraction to 70 Gy in 7 weeks) 6, 3

Treatment Duration Considerations

• Elapsed radiation therapy treatment time is highly predictive of survival 7
• Treatment interruptions during definitive radiation therapy must be avoided, as treatment duration >66 days is associated with significantly worse 5-year survival (15% vs 56% for <55 days) 7
• Deliver at least 1000 cGy/week when using altered fractionation schedules 2

Pre-Radiation Dental Assessment

Mandatory Dental Evaluation

• Dental assessment by a dentist (preferably specialist) is strongly advised prior to therapeutic-intent radiation therapy 4
• Oral assessment should include comprehensive dental, periodontal, and oral radiographic examination performed as early as possible 4
• Teeth with poor prognosis (moderate-severe periodontal disease, periapical disease, caries) within the radiation field should be removed prior to RT 4

Coordination with Radiation Oncology

• Information about planned radiation volume, anticipated dose to mandible/maxilla, and RT start date should be provided to the dental team 4
• If planned extractions will alter vertical dimension of occlusion, perform them before fabricating the immobilization mask 4

Common Pitfalls to Avoid

• Do not delay radiation therapy initiation for routine dental work beyond the 2-week healing window when oncologic urgency exists 4
• Do not start PORT earlier than 4 weeks thinking it will improve survival - there is no benefit and may compromise healing 1
• Do not allow treatment breaks during definitive radiation therapy as this significantly worsens outcomes 7
• Do not use serial monitoring alone for advanced disease when immediate radiotherapy or chemoradiotherapy is indicated 4