What is the recommended initial treatment for a patient with T1 (tumor size) N0 (no regional lymph node metastasis) tongue cancer with perineural invasion (PNI) and no other adverse features?

Treatment of T1N0 Tongue Cancer with Perineural Invasion

For T1N0 tongue cancer with perineural invasion (PNI) and no other adverse features, perform wide local excision with ipsilateral selective neck dissection (levels I-IV), followed by adjuvant radiation therapy to 56-60 Gy to the tumor bed and ipsilateral neck. 1

Primary Surgical Management

Wide local excision (partial glossectomy) with adequate margins (≥5 mm when possible) is the cornerstone of initial treatment. 1 The surgical approach should prioritize achieving clear margins on the first resection, as revised negative margins after re-resection carry a 2.2-fold increased risk of local recurrence compared to initial negative margins (13.1% vs 5.5% local recurrence rate). 2

Neck Management

• Ipsilateral selective neck dissection (levels I-IV) should be performed for well-lateralized tongue lesions, even in clinically N0 disease. 1
• The rationale is compelling: 16.5% of patients with early-stage oral tongue cancer who undergo glossectomy alone subsequently develop cervical metastasis, with only 33% survival and 50% local-regional control when nodes appear later. 3
• In contrast, patients undergoing elective neck dissection who have occult nodal disease (found in 20.4% of cases) achieve 55% survival and 91% local-regional control. 3

Adjuvant Radiation Therapy

Adjuvant radiation is indicated specifically because PNI is present, even in the absence of nodal disease. 1, 4 This represents a critical decision point that distinguishes your case from standard T1N0 disease.

Radiation Parameters

• Total dose: 56-60 Gy using standard once-daily fractionation of 2 Gy per fraction 1, 5
• Target volume: tumor bed and ipsilateral neck (levels I-IV) 1
• For well-lateralized tongue tumors, unilateral radiotherapy is appropriate 1, 5

Evidence Supporting Adjuvant Radiation for PNI

The evidence for adjuvant radiation in pN0/PNI+ patients is substantial:

• PNI independently predicts worse disease-free interval (DFI) and local-regional control (LRC) in pathologically N0 necks. 4
• Among pN0/PNI+ patients, those receiving adjuvant radiation demonstrated significantly improved DFI (6.5 years vs 1.7 years) and LRC (6.7 years vs 1.9 years) compared to surgery alone. 4
• PNI predicts distant recurrence as the most common pattern of failure, with patients 19.4 times more likely to develop distant recurrence when PNI foci density is high. 6
• Notably, PNI significantly adversely affects both survival and local-regional control in early-stage oral tongue cancer. 3

Critical Timing Consideration

Initiate adjuvant radiation within 6 weeks of surgery. 5, 7 Delays beyond this timeframe negatively impact outcomes and should be avoided.

Surveillance Protocol

• Monitor TSH levels every 6-12 months following adjuvant radiation, as hypothyroidism occurs in 20-25% of patients receiving neck irradiation. 1, 5
• Close surveillance for distant metastases is warranted given the PNI-associated risk pattern. 6

Key Pitfalls to Avoid

• Do not pursue observation alone despite negative nodes. The presence of PNI changes the risk profile and mandates adjuvant therapy. 4
• Avoid re-excision attempts if initial margins are close but negative. Revised margins carry worse outcomes than initial negative margins. 2
• Do not delay radiation beyond 6 weeks post-surgery. 5, 7
• Do not treat with surgery and radiation as combined modality for standard T1N0 disease without adverse features, but PNI specifically justifies this approach. 8, 7