Head and Neck Cancer Stages and Classification

This is the seventh page in the Understanding Head and Neck Cancer Guide. This guide was developed by the HealthTree Education Team and was last updated and reviewed on May 22, 2026.

Doctors use "stages" to describe how far cancer has grown and whether it has spread. Knowing the stage of your cancer helps your care team plan the best treatment and understand your prognosis.

Head and neck cancer staging is more complex than for many other cancers because each site (oral cavity, oropharynx, larynx, etc.) has its own staging rules. Head and neck cancers are staged using the AJCC TNM system, which describes the size and extent of the Tumor (T), spread to nearby lymph Nodes (N), and presence of distant Metastasis (M). The combination of T, N, and M is used to assign an overall stage from 0 to IV. For oropharyngeal cancer, separate stagingsystems are used for HPV-positive and HPV-negative disease.

The TNM staging system

The AJCC TNM system is the most widely used system for staging head and neck cancer:

• T (Tumor). Describes the size of the primary tumor and whether it has invaded nearby structures. Ranges from T1 (smallest) to T4 (largest or most invasive).
• N (Nodes). Describes whether the cancer has spread to nearby lymph nodes, and if so, how many, how large, on which side of the neck, and (for HPV-negative cancers) whether the cancer has grown outside the lymph node capsule (extranodal extension).
• M (Metastasis). Describes whether the cancer has spread to distant parts of the body. M0 means no distant spread; M1 means cancer has spread to distant sites such as the lungs, liver, or bones.

Overall stages

The T, N, and M categories are combined to give an overall stage. The exact rules depend on the site and, for the oropharynx, HPV status. In general:

Stage 0 — Carcinoma in situ

Abnormal cells are present in the lining of the mouth or throat but have not invaded deeper tissue. Stage 0 is highly curable.

Stage I — Small, localized tumor

The tumor is small (generally 2 cm or less) and has not spread to lymph nodes or distant sites.

Stage II — Larger localized tumor

The tumor is larger (generally 2–4 cm) but has not spread to lymph nodes or distant sites.

Stage III — Larger tumor or limited lymph node involvement

The tumor is larger than 4 cm, has invaded nearby structures, or has spread to a single lymph node on the same side of the neck. For HPV-negative cancers, this represents a more advanced stage than for HPV-positive cancers.

Stage IV — Advanced disease

Stage IV is divided into substages:

• Stage IVA. The tumor has invaded deeply into nearby tissue or there is more extensive spread to lymph nodes.
• Stage IVB. Very advanced local disease or extensive lymph node involvement, but no distant spread.
• Stage IVC. Cancer has spread to distant parts of the body, such as the lungs, liver, or bones.

Staging for HPV-positive oropharyngeal cancer

HPV-positive oropharyngeal cancer has a much better prognosis than HPV-negative disease, even when the tumor is larger or has spread to lymph nodes. To reflect this, a separate AJCC staging system is used for HPV-positive (p16-positive) oropharyngeal cancers. In this system, many cancers that would be stage III or IV under the HPV-negative system areinstead classified as stage I or II, because the outcomes are similar to early-stage cancers at other sites.

Tumor grade

In addition to stage, the grade of the tumor is described. The grade explains how abnormal the cancer cells look under the microscope:

• Well-differentiated (Grade 1). Cells look more like normal cells and tend to grow more slowly.
• Moderately differentiated (Grade 2). Cells have an intermediate appearance.
• Poorly differentiated (Grade 3). Cells look very abnormal and tend to grow and spread more quickly.

Recurrent head and neck cancer

Head and neck cancer can return after initial treatment. When it does, doctors often classify recurrence by location and timing:

• Local recurrence. Cancer returns at or near the original site.
• Regional recurrence. Cancer returns in nearby lymph nodes in the neck.
• Distant recurrence (metastatic disease). Cancer returns at a distant site, most often the lungs.
• Second primary cancer. A new, separate cancer develops in the head and neck, lung, or esophagus. This is more common in people who have continued to smoke or drink after their initial diagnosis.

Your care team will work with you to determine the best next steps based on the timing and location of recurrence and the treatments you have already had.