Esthesioneuroblastoma Chronicles: A Comprehensive Guide to a Rare Nasal Cancer

Esthesioneuroblastoma, also known as olfactory neuroblastoma, is a rare malignant tumor arising from the olfactory neuroepithelium, the specialized tissue responsible for smell. It accounts for approximately 2% of all sinonasal tumors and has an incidence of 0.4 per million people. This cancer typically occurs in adults between the ages of 35 and 70, with an average age of diagnosis of 53 years.

• Anatomy and Physiology of the Olfactory System: The olfactory system, responsible for our sense of smell, consists of several components:
• Olfactory epithelium: A thin layer of specialized cells lining the upper part of the nasal cavity, known as the cribriform plate.
• Olfactory receptors: These proteins, embedded in the olfactory epithelium, detect odor molecules.
• Olfactory nerves: These nerve fibers carry signals from the olfactory receptors to the olfactory bulb.
• Olfactory bulb: A structure located at the base of the brain that processes olfactory information.

Symptoms of Esthesioneuroblastoma

• The symptoms of esthesioneuroblastoma depend on the size and location of the tumor. Common symptoms include:
• Nasal obstruction: A blocked or stuffy nose is a frequent early symptom.
• Loss of smell (anosmia): As the tumor grows, it can disrupt the olfactory epithelium, leading to a loss of smell.
• Nasal discharge: A bloody or foul-smelling discharge from the nose may occur.
• Facial pain or numbness: The tumor can invade nearby nerves, causing pain or numbness in the face.
• Epistaxis: Nosebleeds may occur as the tumor erodes into blood vessels.
• Proptosis: In advanced cases, the tumor can push the eyeball forward, causing a bulging appearance of the eye.

Diagnosis of Esthesioneuroblastoma: Diagnosis of esthesioneuroblastoma typically involves: Medical history and physical examination: A doctor will review the patient’s medical history and perform a thorough examination of the nose and sinus area.

Nasal endoscopy: A thin, flexible tube with a light and camera is inserted into the nose to visualize the tumor. Biopsy: A tissue sample is removed and examined under a microscope to confirm the diagnosis.

Imaging studies: CT scans, MRI scans, or PET scans may be used to determine the extent of the tumor and assess for any spread to nearby structures.

Staging of Esthesioneuroblastoma

Esthesioneuroblastoma is staged based on the extent of the tumor and the presence of metastasis:

• Stage A: Confined to the nasal cavity
• Stage B: Extends to the paranasal sinuses
• Stage C: Involves the orbit or cribriform plate
• Stage D: Metastasis to lymph nodes or distant sites

Treatment of Esthesioneuroblastoma

The treatment of esthesioneuroblastoma depends on the stage of the disease and the patient’s overall health. Treatment options may include:

Surgery: Surgery is the primary treatment for early-stage esthesioneuroblastoma. The goal of surgery is to completely remove the tumor.

Radiation therapy: Radiation therapy uses high-energy beams to kill cancer cells. It may be used before or after surgery to eliminate any remaining tumor cells.

Chemotherapy: Chemotherapy uses drugs to destroy cancer cells throughout the body. It is typically reserved for advanced-stage esthesioneuroblastoma or in cases where the tumor has spread to other parts of the body.

Prognosis and Survival Rates

The prognosis for esthesioneuroblastoma depends on the stage of the disease at diagnosis. The overall 5-year survival rate is approximately 50%. For patients with early-stage disease, the survival rate is significantly higher, approaching 90%. However, for patients with advanced-stage disease, the survival rate is lower, around 20%.

Recent Advances in Esthesioneuroblastoma Research

Research into esthesioneuroblastoma is ongoing, and new treatment options are being developed. These include: Targeted therapy: This approach uses drugs that target specific molecular abnormalities in cancer cells. Immunotherapy: This treatment harnesses the body’s immune system to fight cancer. Gene therapy: This involves introducing genetic material into cancer cells to alter their behavior or make them more susceptible to treatment.

The reason for the rarity of esthesioneuroblastoma is not fully understood, said Dr Shashidhar K, consultant Onco Surgeon in Hubballi who practices at Samhith Super Specialty Cancer Centre.

However, doctors and studies said that several factors may contribute to its low incidence:

Cell type involvement: Esthesioneuroblastoma arises from the olfactory neuroepithelium, a specialized tissue with limited regenerative capacity. This may explain why tumors originating from this tissue are less common compared to other types of cancer.

Protective mechanisms: The olfactory system is exposed to various environmental factors that could potentially trigger cancer development. However, the olfactory epithelium has built-in protective mechanisms, such as antioxidant and DNA repair enzymes, that may help prevent carcinogenesis.

Genetic predisposition: While genetic mutations have been identified in some esthesioneuroblastoma cases, these mutations are relatively uncommon. This suggests that genetic factors alone are not sufficient to cause this cancer and that other environmental or lifestyle factors may play a role.

Tumor suppressor genes: The expression of tumor suppressor genes, which normally prevent uncontrolled cell growth, may be altered in esthesioneuroblastoma. This could contribute to the development of this cancer.

Immune surveillance: The immune system plays a critical role in eliminating cancer cells. However, esthesioneuroblastoma cells may have mechanisms to evade immune detection, allowing them to grow undetected for longer periods.

Further research is needed to fully elucidate the underlying reasons for the rarity of esthesioneuroblastoma. A better understanding of the factors contributing to its development could lead to more effective prevention and treatment strategies.