Oral Cavity Cancer – TNM Staging and Treatment

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oral-cancer
Oral cavity comprises the lips, buccal mucosa, teeth, gums, bony roof of the mouth, floor of the mouth, oral tongue, and retromolar trigone. The oral cavity structures have a rich lymphatic supply and about 30% of cases are diagnosed with a disease spread to lymph nodes (Level I to III).
More than 90% of oral cavity cancers are SCCs. The ratio of incidences of oral cavity cancers reported in men and women is about 2:1, while the ratio is as high as 15:1 for lip cancers. The most common site of lip cancer is the lip vermilion (border of the lips and the facial skin).
oral cavity cancer normal anatomy

TNM Staging of Oral Cavity Cancer

Once someone is suspected to have oral cavity cancer based on signs and symptoms, further investigations are needed to confirm the diagnosis and stage the disease.

TNM staging system is used to describe the severity of tumor based on the size, extent of invasion, and spread to different body parts. It helps to determine treatment strategy and disease prognosis. It is the most commonly used system for staging oropharyngeal cancer.

“T” stands for “Tumor Size”, “N” for “Lymph Nodes”, and “M” for “Metastasis”. Numbers and/or letters after T (is, 1, 2, 3, 4a, and 4b), N (0, 1, 2, and 3), and M (0 and 1) provide more details about each of these factors. 

T STAGING

Tis – Carcinoma in situ or cancerous lesion is present only in the superficial layer of the oral cavity.

T1 – The primary tumor is </=2 cm in size and the depth of invasion (DOI) is </=5 mm. No spread to nearby lymph nodes or distant body parts.

T1, size less than 2 cm

T2 – The primary tumor is </=2 cm in size with the DOI between 5 mm and 10 mm or primary tumor is >2 cm but </=4 cm with the DOI </=10 mm. 

stage T2

T3 – The primary tumor is >4 cm in size with the DOI between 10 mm and 20 mm.

stage T3T4a – The primary tumor invades adjacent structures and/or DOI > 20 mm.

T4a - invades maxillary sinus

T4a - invades the skin of the face

T4a - invades maxilla or mandible bone

T4b – The primary tumor of any size that has invaded a vital structure, such as masticator space, pterygoid plates, skull base and/or surrounds the carotid artery. 

T4b - invades masticator space, pterygoid plate, internal carotid artery

N STAGING

N0 – No spread of tumor to nearby lymph nodes 

N1 – The disease has spread to a single ipsilateral lymph node measuring </=3 cm without extranodal involvement.

nodal stage N1 - single ipsilateral lymph node measuring </=3 cm

N2a – The disease has spread to a single ipsilateral lymph node measuring >3 cm and </= 6 cm

nodal stage N2a - single ipsilateral lymph node measuring >3 cm and </= 6 cm

N2b – Metastasis to multiple ipsilateral nodes, none >6 cm

nodal stage N2b - multiple ipsilateral nodes, none >6 cm

N2c – Metastasis to bilateral/contralateral lymph nodes, all measuring <6 cm without extranodal involvement. 

nodal stage N2c - bilateral/contralateral lymph nodes, all measuring <6 cm

N3 – The disease has spread to lymph nodes measuring >6 cm or extranodal involvement.

nodal stage N3 - lymph nodes measuring >6 cm

N3 - extranodal involvement

M STAGING

M0 – No spread to distant body parts

M1 – Spread of the tumor to distant body parts.

Once T, N, and M categories are determined through different diagnostic techniques, this information is combined to assign an overall stage (from 0 to IV) to the disease. 

Oral Cavity Cancer Staging Summary

STAGE TNM    
0 Tis N0 M0    
I T1 N0 M0    
II T2 N0 M0    
III T1-2 N1 M0  

  T3 N0-1 M0    
IVA T1-3 N2 M0    
  T4a N0-2 M0    
IVB Any T N3 M0    
  T4b Any N M0    
IVC Any T Any N M1    

 

Oral Cavity Cancer Treatment based on Staging

Apart from the stage of disease, the selection of treatment usually depends upon the location of disease, patient’s preference, performance status of the patient, along with other factors. Following are the preferred treatment approaches for different stages of oral cavity cancer, but the final decision is taken after clinical assessment of the patient by an oncologist.

Non Metastatic Disease Treatment infographic

 

Stage 0

For Stage 0 cancers, surgical resection of the involved site is considered as the standard treatment. The patient should be followed-up closely after treatment for any sign of recurrence.

Stage I and II

For Stage I and II cancers, surgery is considered as the preferred treatment. Surgical resection of the involved site along with lymph node dissection is generally employed. Radiation therapy with or without chemotherapy may be employed after the primary treatment to kill any remaining cancer cells or in the presence of any adverse prognostic features. The patient should be followed-up closely after treatment for any sign of recurrence.

Stage III and IVA

For Stage III to IVA cancers, any of the following 3 approaches can be utilized as the preferred treatment:
1) Start treatment with chemotherapy alone (induction therapy) followed by radiation therapy or radiotherapy + chemotherapy based on the extent of tumor shrinkage with primary treatment.

2) Surgery is employed as the first-line treatment and involves the resection of the primary tumor along with any affected lymph nodes. This is followed by radiation therapy or radiotherapy + chemotherapy based on the presence of any adverse prognostic features.

3) Chemotherapy + radiotherapy or radiotherapy alone can be employed as the primary treatment. Surgery may be employed to remove any remnant cancer tissue.

Stage IVB

For Stage IVB cancer, radiotherapy along with chemotherapy or targeted therapy is usually employed as the first-line treatment. Surgery may be employed if the tumor shrinks sufficiently that it can be removed with surgery. Radiation therapy may be employed as palliative treatment.

Stage IVC

For Stage IVC cancer, chemotherapy, immunotherapy or targeted therapy are the treatment options. Radiation therapy may be employed as palliative treatment.

treatment for metastatic disease infographic

Palliative Treatment

It helps in improving the overall quality of life by providing relief from the symptoms and by reducing the suffering caused by HNC and its treatment. Chemotherapy may be associated with side effects like  nausea/vomitinghair lossfatigue, cytopenias, etc due to its effect on normal body cells apart from cancerous cells.

It is generally given as supportive care for advanced staged HNCs, along with other treatments. It may include but not limited to: drugs to reduce pain and other symptoms such as vomitingfatigue; surgical interventions like gastrostomy or tracheostomy to support nutrition or respiration; support and counselling for speech, swallowing, and oral hygiene-related problems; and radiation therapy to palliate pain, bleeding, obstructive problems, etc.

 

It is very important to assess the benefits of each treatment option versus the possible risks and side effects before making a treatment decision. Sometimes, patient’s choice and health condition are also important to make a treatment choice.

Following are the goals for staging and treatment of oral cavity cancer:

  • Prolongation of life.
  • Reduction of symptoms.
  • Improvement of overall quality of life.

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