Highlight
– In a multicenter retrospective cohort of 755 patients with oral cavity squamous cell carcinoma (OSCC) and pathologic nodal disease, adjuvant chemotherapy added to radiotherapy improved disease-free and overall survival for patients with major extranodal extension (ENE >2 mm) but not for those with minor ENE (≤2 mm).
– Propensity score–matched analyses confirmed no measurable benefit of chemotherapy for minor ENE but showed substantial absolute DFS and OS benefits for major ENE despite no clear improvement in locoregional control.
Background
Extranodal extension (ENE) — tumor infiltration beyond the lymph node capsule — is a well-established adverse prognostic factor in head and neck squamous cell carcinoma (HNSCC). ENE elevates the risk of regional recurrence and distant metastasis and has been a key determinant in postoperative treatment decisions. Major randomized trials two decades ago (RTOG 9501, EORTC 22931) established a benefit of adding systemic platinum-based chemotherapy to postoperative radiotherapy for patients with high-risk features after resection (positive margins and/or ENE), which influenced guideline recommendations for adjuvant chemoradiotherapy (CRT).
More recently, attention has turned to the heterogeneity of ENE. Pathologists and surgeons have categorized ENE by extent — commonly using a 2 mm threshold — into minor (≤2 mm) and major (>2 mm) ENE. This raises a practical question for clinicians: should all ENE be treated the same, or can patients with limited (minor) ENE be spared the added toxicity of chemotherapy with no compromise in outcomes?
Study design
Manojlovic-Kolarski and colleagues performed a retrospective multicenter cohort study across four high-volume head and neck surgery centers in Australia, the United States, and Canada to address this question (JAMA Otolaryngol Head Neck Surg. 2025).
Key features:
– Population: 755 patients with surgically resected oral cavity SCC and pathologic node-positive disease treated from 2005–2018 (final follow-up 2022).
– Exposure: Extent of ENE was restaged from archived pathology and categorized as minor (≤2 mm) or major (>2 mm). Adjuvant therapy followed standard guidelines; patients received postoperative radiotherapy alone or chemoradiotherapy (platinum-based chemotherapy concurrent with radiotherapy) according to treating physicians’ judgment and guideline recommendations.
– Outcomes: Primary oncologic endpoints included locoregional control (LRC), disease-free survival (DFS), and overall survival (OS). The investigators used multivariable Cox regression and propensity score matching to adjust for measured confounders and evaluate the effect of adding chemotherapy within ENE subgroups.
– Statistics: Analyses included univariable and multivariable models, plus propensity score matching to construct comparable treated and untreated cohorts within ENE strata.
Key findings
Population characteristics:
– Total cohort: 755 patients (mean age 61.7 years, 36% female).
– Minor ENE: 126 patients (17%); of these, 50 (39.7%) received adjuvant chemotherapy with radiotherapy.
– Major ENE: 243 patients (32%); of these, 116 (47.8%) received adjuvant chemotherapy.
Multivariable analysis (chemotherapy vs radiotherapy alone):
– Minor ENE: Chemotherapy was not associated with improved outcomes — LRC HR 1.07 (95% CI, 0.49–2.32), DFS HR 0.96 (95% CI, 0.56–1.66), OS HR 0.97 (95% CI, 0.55–1.73).
– Major ENE: Chemotherapy was associated with improved DFS (HR 0.58; 95% CI, 0.41–0.81) and OS (HR 0.61; 95% CI, 0.38–0.98). There was no statistically significant improvement in LRC reported for the major ENE group.
Propensity score–matched analysis (to reduce selection bias):
– Minor ENE matched cohorts: No significant differences in 3-year or median outcomes between CRT and radiotherapy alone — LRC 71% vs 75% (difference 4%, 95% CI -18% to 26%), DFS 56% vs 56% (difference 0%, 95% CI -25% to 25%), OS 57% vs 57% (difference 0%, 95% CI -25% to 25%).
– Major ENE matched cohorts: Chemotherapy improved DFS 33% vs 11% (difference 22%, 95% CI 5%–38%) and OS 41% vs 15% (difference 26%, 95% CI 8%–44%), but not LRC (61% vs 62%; difference 1%, 95% CI -17% to 21%).
Interpretation of results:
– The study supports a clinically meaningful benefit of adding chemotherapy for patients with major ENE, reflected in improved DFS and OS with absolute survival gains in propensity-matched analyses.
– For minor ENE, the lack of demonstrable benefit suggests that routine addition of chemotherapy to adjuvant radiotherapy may be unnecessary, exposing patients to systemic toxicity without survival advantage.
Expert commentary and clinical implications
Clinical relevance:
– Current guideline practice (informed largely by RTOG 9501 and EORTC 22931) historically recommends adjuvant CRT for patients with ENE because these randomized trials grouped ENE as a high-risk feature. However, those trials predated routine stratification of ENE by extent and did not evaluate the minor vs major ENE distinction.
– The new multicenter data provide evidence to refine postoperative decision-making in oral cavity SCC. For patients with major ENE (>2 mm), the data reinforce the contemporary standard of care: adjuvant chemoradiotherapy is associated with improved systemic disease control and survival.
– For patients with minor ENE (≤2 mm), clinicians should weigh expected chemotherapy benefit against toxicity. In the absence of clear survival improvement, a policy of radiotherapy alone may be reasonable for many patients, particularly older individuals or those with comorbidities that increase chemotherapy risk.
Mechanistic considerations:
– The discordance between survival benefit and the lack of clear improvement in locoregional control among major ENE patients suggests chemotherapy may primarily reduce distant relapse or micrometastatic disease rather than dramatically enhancing in-field control. Larger ENE likely reflects higher systemic tumor burden/aggressiveness and therefore derives greater benefit from systemic therapy.
Limitations to consider:
– Retrospective design: Despite robust multicenter sampling, central pathology review, multivariable adjustment, and propensity matching, residual confounding and treatment selection bias cannot be entirely excluded.
– Heterogeneity in treatment: Chemotherapy regimens, radiotherapy techniques and doses, timing, and supportive care may have varied across centers and over the long study period (2005–2018).
– Pathologic measurement variability: ENE extent measurement has interobserver variability; although archived specimens were restaged, some measurement error is inevitable.
– External validity: The cohort includes high-volume surgical centers; outcomes may differ in other settings. Moreover, applicability to non-oral cavity HNSCC subsites (eg, oropharynx, larynx) is uncertain.
Practical recommendations for clinicians
– For patients with pathologic major ENE (>2 mm) in oral cavity SCC after complete resection, adjuvant chemoradiotherapy should remain standard practice when the patient can tolerate systemic therapy, given demonstrated DFS and OS benefits.
– For patients with minor ENE (≤2 mm), consider individualized decision-making. Factors favoring omission of chemotherapy include advanced age, significant comorbidity, borderline performance status, or strong patient preference to avoid chemotherapy-related toxicity. Multidisciplinary tumor boards should review these cases.
– Document pathologic ENE extent explicitly in reports to facilitate evidence-based postoperative planning.
– When omitting chemotherapy in minor ENE, ensure high-quality radiotherapy delivery and close surveillance, and counsel patients regarding the uncertainty and rationale.
Research and guideline implications
– Prospective validation: Randomized controlled trials or prospective registry studies that stratify ENE by extent would provide definitive evidence. Pragmatic trials comparing adjuvant radiotherapy alone versus CRT specifically for minor ENE would be valuable but may be challenging to accrue.
– Biomarkers and imaging: Studies evaluating molecular markers or circulating tumor DNA to identify micrometastatic disease risk could help tailor adjuvant systemic therapy beyond pathologic measures alone.
– Guideline updates: Guideline panels (eg, NCCN) may consider recognizing ENE extent as a modifier in postoperative recommendations, although most panels will await prospective corroboration and further confirmatory data before changing formal recommendations.
Conclusion
This large multicenter cohort study provides clinically actionable evidence that the benefit of adjuvant chemotherapy in surgically treated oral cavity SCC differs by the extent of extranodal extension. Major ENE (>2 mm) is associated with improved DFS and OS when chemotherapy is added to adjuvant radiotherapy, whereas minor ENE (≤2 mm) shows no clear benefit from chemotherapy. Clinicians should use ENE extent, patient fitness, and preferences to individualize adjuvant therapy decisions, while the oncology community should prioritize prospective validation and biomarker-driven risk stratification.
Funding and clinicaltrials.gov
Funding and disclosures: See the original publication (Manojlovic-Kolarski M et al., JAMA Otolaryngol Head Neck Surg. 2025) for detailed funding and conflict-of-interest statements. This analysis is a summary and interpretation of that peer-reviewed report.
References
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