# GUIDELINE OBJECTIVES
To evaluate the appropriateness of, and make recommendations on, routine testing for human papillomavirus (HPV) status in adult patients with primary, or neck nodal metastatic, squamous cell carcinoma (SCC) of the head and neck.

# TARGET POPULATION
Adult patients with squamous cell carcinomas arising in oropharynx, larynx, hypopharynx, nasopharynx, sinonasal tract, or oral cavity subsites or an unknown primary head and neck site.

# INTENDED USERS
This guideline is targeted for: 1. Clinicians involved in the delivery of care of adult patients with head and neck squamous cell carcinoma (HNSCC). 2. Pathologists involved in the evaluation of HNSCCs.

# RECOMMENDATIONS, KEY EVIDENCE, AND JUSTIFICATION

# RECOMMENDATION 1
The tumours of all adult patients presenting with oropharyngeal squamous cell carcinomas should be routinely tested for HPV status.

# Summary of Key Evidence for Recommendation 1
- A meta-analysis showed a definite survival benefit for HPV-positive patients compared to those whose tumour was HPV negative in terms of overall survival (OS) (HR: 0.43 (95%CI: 0.32-0.58), progression-free survival (PFS) (HR: 0.40, 95%CI: 0.28-0.56), and disease-specific survival (DSS) (HR: 0.45 (95%CI: 0.27-0.76). - A published data meta-analysis by Ragin and Taioli (1) demonstrated that patients with HPV-positive oropharyngeal tumours had a 28% reduced risk of death compared to patients with HPV-negative oropharyngeal tumours (HR: 0.72, 95%CI: 0.5-1.0). Similar results were calculated for disease-specific survival (DSS) (HR: 0.51, 95%CI: 0.4-0.7). However, no benefit in overall survival (OS) or DSS was seen in HPV-positive versus negative patients with non-oropharyngeal tumours.

# Justification for Recommendation 1
There is evidence from a meta-analysis of randomized trials that HPV-positivity is a strong predictor of prognosis in patients with oropharyngeal squamous cell carcinoma. In addition, it is likely that HPV status will influence management decisions in the near future and is now regarded as a mandatory stratification factor for clinical trials. Therefore, even though at this time no recommendation can be made to base clinical management decisions on HPV status, the valuable prognostic benefits of HPV testing are sufficient to warrant routine testing.

# Qualifying Statements for Recommendation 1
- The above recommendation only applies to patients with squamous cell carcinoma of the oropharynx, which includes tonsil, base of tongue, soft palate and associated pharyngeal walls. The data and recommendation do not apply to patients with nonoropharyngeal cancers. - Altering management decisions based on results from HPV testing is not recommended beyond the context of a clinical trial at this time.

# RECOMMENDATION 2
It is recommended that the neck nodal tissue of patients with metastatic squamous cell carcinoma to neck nodes from an unknown head and neck primary be routinely tested for HPV status.

# Summary of Key Evidence for Recommendation 2
- Twelve studies (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) found the prevalence of HPV-positive lymph node metastases ranged from 0%-19% in patients with non-oropharyngeal primary sites compared to 66%-87% in those whose primary tumour originated in the oropharynx.

# Justification for Recommendation 2
The evidence indicates that there is relationship between HPV positivity and whether the initial cancer arises in the oropharynx or not. As detection of the primary tumour offers a reduction in morbidity due to the benefits of localized treatment, the additional diagnostic information provided by HPV status is sufficient to warrant routine testing of these tissues.

# Qualifying Statements for Recommendation 2
Currently, there are no standardized protocols or extensive published experience regarding the performance of p16 immunohistochemical (IHC) or HPV in situ hybridization (ISH) in fineneedle aspiration (FNA) or cytology material from metastatic squamous cell carcinoma to cervical lymph nodes.

# RECOMMENDATION 3
It is recommended that HPV status in oropharyngeal SCC be initially determined using immunohistochemical (IHC) staining for p16.
IHC staining for p16 can be considered positive when the following three criteria are met:
- cytoplasmic and nuclear staining - staining is moderate to strong and diffuse - staining is present in at least 70% of tumour cells (See Section 4 for explanation)
A validated polymerase chain reaction (PCR) or in situ hybridization (ISH) technique for highrisk HPV subtypes may be necessary to confirm p16 results in selected cases according to the following algorithm: 

# Technical Considerations for Recommendation 3
While it is not possible to make evidence-based recommendations regarding the minimum set of criteria requiring adherence in a pathology laboratory with respect to HPV testing at this time, the following guidance is offered based on expert opinion and a consensus process by members of the Head and Neck DSG:
- Analysis should be performed on sections from paraffin blocks or unstained slides cut at 4 microns - In cases of metastatic disease, where a core biopsy may not be a possibility, all efforts should be made to obtain enough tissue with FNA to prepare cell blocks.

# Justification for Recommendation 3
The current evidence suggests that PCR, DNA ISH, and IHC staining are all comparable. With no unequivocal evidence exclusively supporting any particular scheme, the Head & Neck Disease Site Group believes this scheme is practical and simple, and it minimizes the impact of testing on available pathology resources and is appropriate until such time as further evidence becomes available. The Head & Neck DSG acknowledges that the algorithm may be considered controversial by some, but it is believed to address the proficiencies that are most readily available in laboratories across the province.

# Qualifying Statements for Recommendation 3
- The Head & Neck DSG considers quality assurance and quality control in HPV-status testing to be paramount. As such, all testing should be carried out in licensed and accredited laboratories, and test results should be interpreted by experienced pathologists/scientists. Laboratories need to follow proper quality control and participate in external proficiency testing to ensure test accuracy. Further discussion of specific quality and proficiency parameters necessary for individual laboratories performing HPV-status testing is beyond the scope of this guideline. - Qualitative HPV PCR assay detection alone should be avoided - The above recommendations do not apply to samples from dental procedures.

# FUTURE RESEARCH
Insufficient data currently exist to assess the prognostic benefit of HPV positivity in SCC of the larynx, hypopharynx, nasopharynx, sinonasal tract and oral cavity. There is evidence in the literature to suggest that the prevalence of HPV in these subsites may be higher than originally believed. Meta-analyses (1,27,28) report a pooled prevalence in the oral cavity and the larynx as high as 40% and 24%, respectively. Lip and oral cavity, pharynx, larynx, nasopharynx and lymph nodes combined have a reported pooled HPV prevalence of 32%. Such values warrant further prospective local data collection via the creation of a provincial patient registry to establish the prevalence of HPV-associated SCC and to clarify the prognosis associated with HPV positivity in these patients. This will ensure the acquisition and availability of evidence upon which future clinical decisions can be based. Updating All PEBC documents are maintained and updated as described in the PEBC Document Assessment and Review Protocol.