HPV Independent Squamous Cell Carcinoma of the Oropharynx: Understanding Your Pathology Report

Section Editor: Jason Wasserman MD PhD FRCPC
July 26, 2026

HPV-independent squamous cell carcinoma is a type of cancer that develops in the oropharynx, the part of the throat behind the mouth, and that is not caused by human papillomavirus (HPV). The oropharynx includes the tonsils, the base of the tongue (the back third of the tongue), the soft palate, and the back wall of the throat. The cancer starts in squamous cells, the flat cells that line this part of the throat.

The word “HPV-independent” matters because it separates this cancer from HPV-associated squamous cell carcinoma, which is a different disease with a better outlook. Both start from squamous cells in the same part of the throat, but they have different causes, look different under the microscope, are staged using different systems, and have different outcomes. Knowing which type you have shapes how the cancer is treated and what to expect, so if you are unsure which one your report describes, that is a good first question for your doctor.

This article explains the findings you are likely to see on a pathology report for HPV-independent squamous cell carcinoma of the oropharynx, what each one means, and why it matters for your care.

What causes HPV-independent squamous cell carcinoma of the oropharynx?

HPV-independent squamous cell carcinoma of the oropharynx develops when the squamous cells lining the throat are damaged repeatedly over many years. Each round of damage and repair leaves behind small errors in the cells’ genetic material, and once enough of these build up, the cells begin to grow uncontrollably. The most common sources of that damage are:

Tobacco. The single most important risk factor, in any form.
Alcohol. Heavy use raises risk on its own, and combining heavy drinking with heavy smoking raises it far more than either alone.
Previous radiation to the head and neck. Radiation given years earlier for another condition can raise the risk of a cancer developing in the treated area.
A weakened immune system. This includes long-term immune suppression after an organ transplant.

Unlike HPV-associated oropharyngeal cancer, which often develops in people with little or no history of tobacco or alcohol use, this type is strongly linked to these exposures. Rarely, inherited conditions that impair the body’s ability to repair damaged DNA also play a role.

What are the symptoms of HPV-independent squamous cell carcinoma of the oropharynx?

The symptoms of HPV-independent squamous cell carcinoma of the oropharynx depend on the size and location of the tumor. Common symptoms include:

A sore throat that does not go away and does not improve with antibiotics
Pain or difficulty swallowing
Ear pain on one side, with a normal ear examination
A lump or thickening in the neck, which may mean the cancer has spread to a lymph node
A visible mass on the tonsil or the back of the tongue
Voice changes or hoarseness
Unexplained weight loss

There is a useful difference between the two types. In HPV-associated oropharyngeal cancer, the original tumor is often very small, and the first sign is usually an enlarged lymph node in the neck. HPV-independent tumors are more often visible as a larger mass in the throat by the time they are found.

How is the diagnosis made?

The diagnosis of HPV-independent squamous cell carcinoma of the oropharynx is made when a pathologist examines a tissue sample under the microscope. The sample is obtained by biopsy from the oropharynx, most often the tonsil or base of the tongue, or from an enlarged lymph node in the neck. If a neck lymph node is sampled first using a fine needle aspiration, a biopsy of the throat is usually performed afterward to confirm where the cancer started.

Under the microscope, this cancer is typically keratinizing, meaning the cancer cells produce keratin, a tough protein normally made by squamous cells. This is the main microscopic difference from HPV-associated oropharyngeal cancer, which is usually nonkeratinizing. The pathologist also performs testing to confirm the cancer is not linked to HPV, described in the next section. Once the diagnosis is confirmed, imaging such as a CT scan, MRI, or PET-CT shows how far the tumor extends and whether lymph nodes are involved.

p16 and HPV testing

Every squamous cell carcinoma of the oropharynx is tested for HPV, because the result determines which staging system is used and what outcome to expect. The testing is done on the tumor tissue, and the results appear on your pathology report as one or both of the following:

p16: negative. p16 is a protein that builds up in large amounts inside cells infected with high-risk HPV, so it is used as a stand-in marker for the virus. It is measured using immunohistochemistry, a test that uses antibodies to detect specific proteins in tissue. A positive result means strong staining in at least 70% of the tumor cells. In HPV-independent cancer, the result is negative, meaning the staining is absent, weak, or present in only scattered cells.
HPV in situ hybridization or PCR: negative. These tests look for the genetic material of the virus directly inside the tumor cells. They are not performed on every case, but may be added to confirm a p16 result, particularly when the p16 result and the appearance of the tumor do not fit together as expected.

A negative result on these tests, together with invasive squamous cell carcinoma under the microscope, is what establishes the diagnosis of HPV-independent squamous cell carcinoma. If your report shows a positive p16 result, the HPV-associated squamous cell carcinoma article applies to you.

Histologic grade

The grade describes how closely the cancer cells still resemble normal squamous cells and how much keratin they produce. HPV-independent squamous cell carcinoma of the oropharynx is graded, unlike the HPV-associated type, which is not graded because its cells all share a similar appearance. Your report will use one of these terms:

Well differentiated. The cells closely resemble normal squamous cells and produce abundant keratin. These tumors tend to grow more slowly.
Moderately differentiated. The cells vary more in size and shape and produce less keratin.
Poorly differentiated. The cells look very different from normal squamous cells and produce little or no keratin. These tumors tend to grow more quickly and spread more readily.

Grade is one of the findings your treatment team considers, but it is a weaker predictor than the stage of the cancer, the margins, and whether lymph nodes contain cancer.

Tumor extension into nearby structures

Your report will describe whether the tumor has grown beyond where it started in the oropharynx into anything nearby. As it grows, it can reach the walls of the throat, the soft tissue of the neck, the larynx (voice box), the deep muscles of the tongue, the hard palate, or the mandible (lower jaw). Growth into these structures raises the tumor stage and generally means a larger operation, and it is one of the findings the treatment team weighs when planning treatment after surgery.

Perineural invasion

Perineural invasion means cancer cells are growing along or around a nerve. Nerves run throughout the throat and neck, carrying signals for sensation and movement, and they provide a path that cancer cells can follow beyond the visible edge of the tumor. Your report will state whether perineural invasion is present or absent. When present, it is linked to a higher chance of the cancer returning at the original site, and it is one of the findings that often leads the treatment team to consider radiation after surgery.

Lymphovascular invasion

Lymphovascular invasion means cancer cells have entered a small blood vessel or lymphatic channel near the tumor. These vessels can carry cancer cells to the lymph nodes or, less often, to distant organs. Your report will state whether it is present or absent. When present, it is considered an adverse finding and may influence the treatment options discussed with you.

Surgical margins

Margins are the cut edges of the tissue removed during surgery. The goal is to remove the tumor along with a rim of normal tissue, so that no cancer is left behind. The pathologist inks the edges of the removed tissue and measures how close the tumor comes to each one.

Negative (clear) margin. No cancer cells at the inked edge. This suggests the tumor was removed completely.
Close margin. Cancer cells come within a few millimeters of the edge without reaching it. This raises the chance of the cancer returning at the same site.
Positive (involved) margin. Cancer reaches the inked edge, meaning some may remain. This is one of the strongest reasons the treatment team considers further surgery or radiation.

In HPV-independent oropharyngeal cancer, a positive or close margin is a high-risk finding, and together with other adverse findings it often leads to a discussion about radiation combined with chemotherapy after surgery.

Lymph nodes

Lymph nodes are small immune organs that filter fluid draining from the tissues. The oropharynx drains to lymph nodes on both sides of the neck, so a neck dissection to remove a group of these nodes is usually performed as part of surgery. The pathologist examines each node and reports:

How many lymph nodes were examined and how many contained cancer. Usually written as a ratio, such as 3 of 32. The risk of recurrence rises with the number of involved nodes.
The size of the largest deposit of cancer. Measured in millimeters.
Extranodal extension. This means cancer cells have broken through the outer capsule of a lymph node into the surrounding tissue.

Extranodal extension is a particularly important finding in HPV-independent disease. It is one of the strongest predictors of the cancer returning, and it is among the findings most likely to lead the treatment team to recommend chemotherapy given together with radiation after surgery. Lymph node involvement carries more weight in HPV-independent cancer than in the HPV-associated type, which is one reason the two use separate staging systems.

PD-L1

PD-L1 is a protein that some cancer cells display on their surface to avoid being attacked by the immune system. Immunotherapy drugs called checkpoint inhibitors, such as pembrolizumab (Keytruda) and nivolumab (Opdivo), block this signal so the immune system can recognize and attack the cancer.

PD-L1 testing is not needed to make the diagnosis. It is generally performed when the cancer cannot be removed by surgery, has returned after treatment, or has spread to distant parts of the body. The result is reported as a Combined Positive Score, or CPS, a number that reflects how many cells in and around the tumor show PD-L1. A CPS of less than 1 is considered negative. A CPS of 1 or higher is considered positive and means immunotherapy may be an option, and a higher score suggests the cancer is more likely to respond. Your report will give the specific number. You can read more in the article on PD-L1 testing in cancer.

Pathologic stage (pTNM)

The pathologic stage describes how far the cancer has spread, based on the tissue examined under the microscope. It uses the TNM system, which has three parts: T for the size and extent of the primary tumor, N for spread to the lymph nodes in the neck, and M for spread (metastasis) to more distant parts of the body. The letter “p” in front, as in pT and pN, means the stage was determined by examining tissue rather than by imaging alone.

HPV-independent oropharyngeal cancer uses a staging system based on tumor size and how far it has grown, similar to the one used for squamous cell carcinoma of the oral cavity. This is different from the system used for HPV-associated oropharyngeal cancer, which is based mainly on the number of involved lymph nodes. The difference reflects the greater weight that lymph node spread carries in HPV-independent disease.

Tumor stage (pT)

pT1. Tumor 2 cm or smaller.
pT2. Tumor larger than 2 cm but not more than 4 cm.
pT3. Tumor larger than 4 cm, or extending to the surface of the epiglottis.
pT4a. Tumor has grown into nearby structures such as the larynx, the deep muscles of the tongue, the hard palate, or the jawbone.
pT4b. Tumor has grown into deeper structures such as the skull base, or surrounds the carotid artery. These tumors usually cannot be removed completely by surgery.

Nodal stage (pN)

pN0. No cancer found in any lymph node.
pN1. Cancer in a single lymph node on the same side as the tumor, 3 cm or smaller, without extranodal extension.
pN2. Cancer in a larger node, in more than one node, or in nodes on both sides of the neck, in ways set out by the staging system. This category also includes a single small node on the same side that shows extranodal extension.
pN3. Cancer in a node larger than 6 cm, or extranodal extension in any node beyond the situation covered by pN2.

Your report may not include the M category, because spread to distant parts of the body is usually determined by imaging rather than by the pathologist. Your treatment team combines the pathology findings with your scans to arrive at the overall stage. You can read more in the article on TNM staging.

What is the prognosis for HPV-independent squamous cell carcinoma of the oropharynx?

Prognosis means the likely course and outcome of a disease. For HPV-independent squamous cell carcinoma of the oropharynx, the outlook is less favorable than for HPV-associated oropharyngeal cancer at a comparable stage. The same tumor size or the same number of involved lymph nodes carries a greater risk of the cancer returning in HPV-independent disease, which is why the two cancers are staged separately.

Reported five-year survival for locally advanced HPV-independent oropharyngeal cancer is generally in the range of 30 to 50%, compared with roughly 70 to 85% for HPV-associated disease at a similar stage. Even early-stage HPV-independent tumors carry a higher risk of returning than their HPV-associated counterparts. These are averages drawn from large groups of patients treated over many years. They describe general patterns and cannot predict what will happen for any one person.

The findings on your report linked to a higher risk of the cancer returning are:

Extranodal extension. The strongest single predictor of recurrence, and a common reason for adding chemotherapy to radiation after surgery.
Positive or close surgical margins. Associated with a higher rate of the cancer returning at the original site.
Perineural invasion. Increases the risk of the cancer returning locally.
Higher tumor stage. Reflects deeper growth or extension into nearby structures.
Multiple involved lymph nodes or large deposits of cancer within them. Risk rises with each additional involved node.
Poorly differentiated grade. Associated with faster growth, though less powerfully than stage or lymph node findings.

One factor is within your control. Continuing to use tobacco after treatment worsens outcomes and raises the risk of a second, separate cancer developing in the head, neck, or lungs. Stopping tobacco and limiting alcohol before, during, and after treatment is one of the most effective steps available, and support for quitting is a standard part of care.

What happens after the diagnosis?

After the diagnosis is confirmed, your pathology report is reviewed together with your imaging and overall health, usually by a team that includes head and neck surgeons, radiation oncologists, medical oncologists, and pathologists. The report does not decide treatment on its own, but several of its findings shape the options the team will discuss with you.

Surgery with neck dissection is often the main treatment for tumors that can be completely removed. When the report shows high-risk findings such as positive or close margins, perineural invasion, extranodal extension, or several involved lymph nodes, the team may discuss radiation combined with chemotherapy after surgery. For some patients, particularly those with large tumors or tumors involving critical structures, radiation with chemotherapy without surgery may be the preferred approach. For cancer that has returned or spread, options include chemotherapy, the targeted drug cetuximab, and immunotherapy.

Supportive care runs alongside treatment. This includes a dental assessment before radiation, nutrition support, and therapy for swallowing and speech. Follow-up involves regular examination and imaging, most intensively in the first two to three years, and continues long term because of the ongoing risk of a new cancer developing.

Questions to ask your doctor

Was my cancer confirmed as HPV-independent, and what did the p16 test show?
Where in my oropharynx did the cancer start?
What was the size of the tumor, and what is the grade?
Did the tumor grow into any nearby structures?
Were the surgical margins clear?
Was perineural or lymphovascular invasion found?
How many lymph nodes were removed, and how many contained cancer?
Was extranodal extension present?
What are my pT and pN categories, and what is my overall stage?
Was PD-L1 testing done, and what was the CPS result?
Is radiation or chemotherapy being considered after surgery?
How will my swallowing, speech, and dental health be supported?
What help is available to me for stopping tobacco and reducing alcohol?
How often will I be followed, and for how long?