Sinonasal Neuroendocrine Carcinoma, from the CureRays guide library.

Sinonasal neuroendocrine carcinoma is a rare, aggressive cancer of the nasal cavity and sinuses arising from hormone-sensing (neuroendocrine) cells, usually treated with chemotherapy and radiation — often with proton or intensity-modulated radiation to protect the eyes and brain.

What it is.

Sinonasal neuroendocrine carcinoma is a rare cancer that develops in the nasal cavity and the air-filled sinuses around the nose, arising from neuroendocrine cells — specialized cells that can sense the environment and release chemical signals. It is distinct from the more common sinus cancers and from olfactory neuroblastoma (esthesioneuroblastoma), although these can look similar and require expert pathology to tell apart. It tends to grow quickly and can extend toward the eyes, the base of the skull, and the brain because of the cramped, delicate anatomy of this region. The most aggressive form, small-cell neuroendocrine carcinoma, behaves much like small-cell lung cancer and is treated similarly. Because the tumor sits close to critical structures, treatment usually combines chemotherapy and precisely targeted radiation, with surgery in selected cases, delivered by an experienced head-and-neck team.

How radiation treats it.

Radiation damages the DNA inside cancer cells so they can no longer divide and grow. Sinonasal neuroendocrine carcinoma, especially the high-grade and small-cell forms, is sensitive to radiation, which makes radiation a central treatment — used with chemotherapy when surgery isn't possible, after surgery to clear microscopic disease, and to relieve symptoms in advanced disease. Because the tumor sits inches from the eyes, optic nerves, and brain, precision is essential: intensity-modulated radiation and proton therapy shape the dose tightly around the cancer while sparing these critical structures to protect vision and brain function. Radiation is painless during delivery, given over several weeks of daily sessions, and external-beam treatment leaves no radioactivity in the body. For small-cell types, doctors may also consider radiation to high-risk areas such as the brain, as is done in small-cell lung cancer.

The ways we can treat it.

Intensity-modulated radiation (IMRT). Beams are shaped tightly around the tumor to deliver a high dose while sparing the eyes, optic nerves, and brain that sit right next to the sinuses.

Proton therapy. Protons stop at a set depth, reducing dose beyond the tumor — valuable here for protecting vision and brain tissue near the sinuses.

Prophylactic cranial / neck radiation (selected small-cell). For small-cell types that resemble small-cell lung cancer, radiation to the brain or neck may be considered to prevent spread to those high-risk sites, as in lung cancer.

Questions we hear often.

How is this different from olfactory neuroblastoma? Both arise in the upper nasal region and can look similar, but they are different cancers with different behavior and treatment. Expert pathology — often with special stains and molecular testing — is needed to tell sinonasal neuroendocrine carcinoma apart from olfactory neuroblastoma (esthesioneuroblastoma) and from undifferentiated carcinoma, because the right diagnosis guides the right treatment.

Will treatment affect my eyes or vision? Because the sinuses sit right next to the eyes and optic nerves, protecting vision is a major goal. Modern radiation techniques like IMRT and proton therapy are designed to deliver a strong dose to the tumor while sparing the eyes and optic nerves as much as possible. Your team will discuss the specific risks for your tumor's location.

Why is chemotherapy often used? High-grade and small-cell forms of this cancer can spread, so chemotherapy is used to treat disease throughout the body and to make radiation more effective. The combination of chemotherapy and radiation gives the best chance of controlling these aggressive tumors.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.