Management of unilateral head and neck carcinoma of unknown primary: Retrospective analysis of the impact of postoperative radiotherapy target volumes

Radiotherapy to the neck after neck dissection for head and neck squamous cell carcinoma from an unknown primary: A narrative review

PURPOSE

To conduct a comprehensive narrative review of the evidence for radiotherapy target volumes to the neck, after neck dissection, for head and neck squamous cell carcinoma from an unknown primary (HNSCCUP). Inclusion or exclusion of mucosal irradiation is not the focus of interest for this review article.

MATERIALS AND METHODS

Literature (PubMed-Medline, EMBASE database and Cochrane library) was searched using the relevant keywords. The search results were limited to the studies published in year 2000 or after.

RESULTS

Eight studies met the inclusion criteria. All studies were retrospective in nature. The incidence of contralateral recurrence rates in the untreated neck when the involved neck only is treated remains very low (0%-10%). Survival has improved over the past two decades, most likely due to improved diagnostic techniques and the increase in incidence of HPV-related disease.

CONCLUSION

Given the rarity of disease, level one evidence from randomised controlled trials is lacking. Available data are retrospective but support unilateral post-operative radiotherapy as a treatment option in selected cases.

Is bilateral radiotherapy necessary for patients with unilateral squamous cell carcinoma of unknown primary of the head and neck region?

Background and Purpose

Squamous cell carcinoma of unknown primary (SCC-CUP) of the head and neck region remains a clinical challenge, with uncertainty surrounding the necessity of contralateral irradiation of cervical lymphatic drainage in cases of unilateral involvement.

Materials and Methods

A retrospective study was conducted at the Department of Radiation Oncology, University Medical Center Mainz, on a cohort of 50 patients with unilateral SCC-CUP of the head and neck region treated between 2005 and 2019. 30 patients received bilateral and 20 received unilateral cervical radiotherapy. The majority (n = 38, 76 %) were treated with modern IMRT/ VMAT (Intensity-modulated Radiation Therapy/ Volumetric Modulated Arc Therapy) techniques.

Results

After a median follow-up of 64.5 months, locoregional recurrences occurred in 26 % of cases (n = 13/50), all of which were ipsilateral and predominantly within the volume of the previous irradiated CTV (clinical target volume) (85 %, n = 11/13). No patient treated unilaterally developed a contralateral recurrence in the neck. After 3 years, we observed 7 locoregional recurrences in the bilateral irradiated group (n = 7/30, 23 %), and 5 locoregional recurrences in the unilateral irradiated group (n = 5/20, 25 %). After 3 years, 12 patients had died in the bilateral irradiated group (n = 12/30, 40 %), and 7 in the unilateral irradiated group (n = 7/20, 35 %). 7 Patients showed distant metastases after 3 years in the bilateral irradiated group (n = 7/30, 23 %), and 2 in the unilateral irradiated group (n = 2/20, 10 %). Locoregional control (LRC) at 5 years was 66.2 % in the bilaterally irradiated group, and 70.0 % in the unilaterally irradiated group. Overall survival (OS) was 52.6 % (bilateral) and 64.0 % (unilateral). Distant metastasis-free survival (DMFS) was 74.7 % (bilateral) and 84.4 % (unilateral). No significant differences were observed in OS (p = 0.37), LRC (p = 0.91), and DMFS (p = 0.91) between the groups.Acute toxicity ≥ °2 accordingly CTCAE (Common Terminology Criteria of Adverse Events) was high with 97% while late toxicity ≥ °2 was moderate with 31%. There was no statistically significant difference between the group of unilateral and bilateral irradiated patients.

Conclusion

These data suggest that contralateral cervical irradiation may be of limited benefit in patients with SCC-CUP, as recurrences occured ipsilaterally, and predominantly within the area of prior irradiation. Unilateral irradiation seems to be adequate for carefully selected patients.

Management of unknown primary head and neck cancer with radiation therapy in the era of human papillomavirus (HPV): No longer cutting down the tree to get an apple

PURPOSE

Given the central role that radiation has in the management of head and neck squamous cell carcinoma of unknown primary origin, it is imperative to review how treatment paradigms have been refined and continue to evolve in the modern era.

METHODS AND MATERIALS

This study was designed based on the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) statement. A literature search of peer-reviewed publications was undertaken to identify works pertaining to the use of radiation for squamous cell carcinoma of unknown primary origin presenting as cervical lymph node metastases. Articles published from January 2002 to January 2023 with full text available on PubMed and restricted to the English language and human subjects were included. The full bibliographies of identified articles were reviewed and irrelevant studies were removed.

RESULTS

While such breakthroughs as intensity-modulated radiotherapy, positron emission tomography, biomarker testing with immune-histochemistry, and minimally invasive surgical techniques such as transoral robotic surgery have fundamentally changed the approach to this disease in recent decades, controversies still exist with respect to the manner in which radiation is delivered. Although the incidence of head and neck unknown primary cancer is relatively low, questions regarding the necessity of comprehensive radiation using the age-old standard method of targeting the bilateral necks and entire pharyngeal axis to encompass all putative sites of mucosal disease persist.

CONCLUSIONS

Prospective evidence is lacking, and the available studies have been complicated by such factors as the relatively limited sample sizes, as well as the variability in work-up, treatment, inclusion criteria, and follow-up. Regardless, advances in science and technology have ushered in more precise approaches with a high degree of customization, particularly given the increased proportion of patients presenting with human papillomavirus-related disease.

Influence of postoperative radiotherapy target volumes in unilateral head and neck carcinoma of unknown primary: A multicentric study using propensity score

OBJECTIVE

To compare the impact of two radiation modalities on loco-regional control, survival and tumour emergence, after node dissection for an unilateral head and neck carcinoma of unknown primary (HNCUP).

MATERIALS AND METHODS

This is a multicentric retrospective study of 138 patients with unilateral HNCUP treated between 2002 and 2017. The absence of primary tumour was assessed by a systematic panendoscopy and positron emission tomography. Neck dissection was initially performed for all patients. Radiation Therapy was delivered on ipsilateral lymph node areas in 62 cases (44%: UL-RT group) and on bilateral lymph node areas and the entire pharyngeal mucosa in 77 cases (56%: COMP-RT group). Impact of radiation modalities on locoregional control and overall survival was assessed using propensity score matching method in order to balance baseline characteristics between the two groups.

RESULTS

The population included 80.4% men, 80.4% smokers, 32.6% P16 positive tumours and 71.0% extracapsular extension. After a median follow-up of 5 years, the locoregional control rate was 80.3% in the UL-RT group and 75.3% in the COMP-RT group (p = 0.688). The corresponding rate of contralateral lymph node recurrence was 0% versus 2.6% (p = 0.503) and the rate of tumour emergence was 11.5% versus 9.1% (p = 0.778). No significant difference was observed between the UL-RT and the COMP-RT groups for overall survival (p = 0.9516), specific survival (p = 0.4837) or tumour emergence (p = 0.9034).

CONCLUSION

UL-RT seems to provide similar outcomes as COMP-RT in unilateral HNCUP post-operative management.