Oral Cancer Investigation And Treatment Procedures Essay Questions
Question 1. Describe the principle, mechanism, and types of radiation therapy applied for oral cancer.
Answer:
Table of Contents
Radiation Therapy:
- Principle:
- Radiation damage the cellular DNA, cell membrane, chromosomes, enzymes, and proteins either directly by ionization or indirectly by generating free radicals (H+, OH-) from the radiolysis of water.
- Affected cells either die or become incapable of undergoing cell division and maintaining their integrity.
Read And Learn More: Oral Medicine and Radiology Question And Answers
During the treatment course, normal cells get protected because:
- The reparative ability following radiation injury is much higher for normal cells than malignant cells.
- Cancerous cells are in a rapidly dividing phase (higher growth potential) which makes them more susceptible to therapeutic effects.
The therapeutic effects of radiation depend on:
- Total dose
- Number of fractions/day
- Dose/fraction
- Total treatment time (time dose frac¬tion—TDS).
Radiotherapy for oral cancer:
- Squamous cell carcinoma is radio¬sensitive and is curable in the early stage.
- Poorly-differentiated tumors respond better than well-differentiated types because of increased cell division rate.
- Exophytic, well-oxygenated tumors are more responsive than infiltrative and invasive tumors.
- Squamous cell carcinoma restricted to the mucosa is more highly curable than one with bone involvement.
- Small cervical nodes are managed with radiotherapy, but the extensive involvement of cervical nodes needs combination therapy.
Radiation treatment is determined by:
- Site, size, and total volume of tissue to be irradiated.
- Patient’s tolerance.
- Total number of days of treatment.
- Protecting the normal, uninvolved tissues and organs.
Radiotherapy Types:
- Teletherapy (External-beam Radiation Therapy)
- Teletherapy Indication: Primary tumors of the posterior- third of the tongue, oropharynx, and tonsillar pillar.
Teletherapy Treatment planning:
- Localization of a tumor and radiation planning: The margins of a tumor are marked with radiopaque lead wire or gold or by a tattoo on facial skin.
- If multiple fractions are planned, the area of treatment needs to be immobilized by using head holders, bandages or custom acrylic shells.
- An oral device with or without a tongue depressor is combined with these materials to position the mandible into or out of the radiation field.
- The commonly used type is electron beam therapy and is applied in:
- Parallel opposed field (bilateral)—for more extensive tumors and tumors crossing the midline.
- Wedged-pair field for unilateral lesions.
- The usual dose of epithelial neoplasms: Is 1.8-2 Gy/fraction for 5 weeks for a total dose of 6,000-6,500 cGy.
- Hypofractionation protocol: It is 100¬150 cGy twice daily for a total dose of 5,000 cGy in 3 weeks.
Brachytherapy (Implant techniques): The implant technique of radioisotopes is used to deliver radiation to a localized lesion.
Brachytherapy Indications:
- A tumor involving the anterior 3rd of the tongue.
- A booster dose of radiation to a specific site.
- For recurrent tumors.
- The radioisotopes used are Cesium, iridium, and gold—192Ir, 137Cs, 125I, 198Au.
Brachytherapy Treatment method:
- Direct implantation technique—To deliver radiation.
- After the loading technique—The isotope is implanted using previously inserted guide tubes.
Advantages of brachytherapy: The implan¬ted radio isotopes deliver radiation in a relatively low dose at the immediate locality, so there is minimal radiation exposure to adjacent structures.
Question 2. Briefly describe the pathogenesis of oral cancer.
Answer: Pathogenesis of oral cancer is given
Cellular Level: When the cells are exposed to irritant stimuli, they respond by a series of changes like cellular atypia, epithelial dysplasia, carcinoma-in-situ, and oral carcinoma.
Molecular Level:
- Genetic mutations in proto-oncogenes and tumor suppressor genes result in malig¬nant changes.
- Proto-oncogenes increase cell growth and differentiation thereby provoking carcinomatous changes.
- Proto-oncogenes responsible for oral cancer include ras, MYC gene, bcl1, bcl2, CK8, and CK19.
- Tumor suppressor genes (TSG) negatively regulate cell division and differentiation.
- These gene products inhibit the cell cycle when DNA damage occurs following exposure to carcinogens or infections with oncogenic viruses. If DNA damage is severe and irreparable, the TSG proteins may subject these cells to apoptosis (programmed cell death).
- Tumor suppressor genes responsible for oral cancer include p53 and p21.
- If p53 is not expressed or mutilated, there will be no break in the cell cycle and mitosis progress. Most of the oral cancers have a p53 mutation.
Question 3. Briefly describe the different forms of radiotherapy available for head and neck cancers.
Answer:
Particle Radiation Therapy:
- It is the traditional method of delivering therapeutic radiation and includes both proton and neutron therapy.
- Proton rays are advantageous in their ability to deliver the dose to conform to the shape of the tumor.
Stereotactic Radiotherapy: It uses single high-dose radiation delivery directly to the tumor mass. The technique is precise and painless, for example, gamma knife surgery.
Intraoperative Electron Radiation Therapy:
- This technique delivers high single-dose radiation to the tumor cells during surgery.
- Intraoperative electron radiation therapy (IOERT) is called as precision radiotherapy as it avoids radiation to healthy tissues surrounding the tumor site.
- Intraoperative electron radiation therapy also reduces the treatment duration and side effects of radiotherapy.
Image-guided Radiotherapy (IGRT): This is valuable in avoiding any part of the tumor or tumor-invaded tissue skipping down the path of radiation and treatment failure.
3D Conformal Radiation Therapy: Radiotherapy is supported by CT and MRI to deliver the radiation from multiple angles to reach tumor in three-dimensional aspects and at the same time preserve the healthy tissues.
Intensity-modulated Radiotherapy:
- Intensity-modulated radiotherapy (IMRT) is delivered by the use of computer-assisted linear accelerators with static or multileaf collimators or volumetric arc-modulated therapy.
- It provides appropriate radiation dose accurately to the three-dimensional shape of the tumor, by protecting the surrounding healthy tissues. This technique is known as tomotherapy.
- Intensity-modulated radiotherapy is at present used for the treatment of head and neck tumors and tumors of the central nervous system.
Radioimmunotherapy:
- It is a form of radiation therapy used with immunotherapy. A monoclonal antibody is combined with a radioactive material (such as iodine-131, yttrium-90) and is injected into the patient’s blood.
- When they reach the tumor site, monoclonal antibodies bind to the tumor cells and deliver high-dose radiation. This type of radiation delivery is also known as targeted radiotherapy.
- Currently used in treating lymphoma cases.
Oral Cancer Investigation And Treatment Procedures Multiple Choice Questions
Question 1. Following the complete cessation of smoking, the risks of developing cancer will be reduced after
- 1.6 years
- 5-10 years
- 15-20 years
- 3.2 years
Answer: 2. 5-10 years
Question 2. Hit and run effect is associated with
- Chemical oncogenes
- Proto-oncogenes
- HSV oncogene
- Activated oncogene
Answer: 3. HSV oncogene
Question 3. The most commonly proven viral infection in oral carcinogenesis is
- HSV-2
- HHV-8
- HPV-16
- EBV -2
Answer: 3. HPV-16
Question 4. Carcinoma of the gingiva-buccal complex is known as
- Indian oral cancer
- Rodent tumor
- Aboriginal cancer
- Trigone cancer
Answer: 1. Indian oral cancer
Question 5. Indian oral cancer is due to (or) etiology for Indian oral cancer is
- Bidi smoking
- Placement of tobacco quid
- Eating spicy food
- Tobacco and alcohol consumption
Answer: 2. Placement of tobacco quid
Question 6. IMRT is chiefly indicated for
- Non-Hodgkin’s lymphoma
- kaposi’s sarcoma
- Multiple myeloma
- Nasopharyngeal carcinoma
(Note: IMRT refers to Intensity-modulated radiation therapy).
Answer: 4. Nasopharyngeal carcinoma
Question 7. The most adverse effect in using methotrexate is
- Bone marrow depression
- Folic acid deficiency
- Osteonecrosis
- Altered taste sensation
Answer: 1. Bone marrow depression
Question 8. A biopsy is contraindicated for
- Bony lesions
- Necrotic lesions
- Vascular lesions
- Glandular lesions
Answer: 3. Vascular lesions
Question 9. The preferred imaging modality for head and neck tumor is
- Computed tomography
- Cone-beam computed tomography
- Magnetic resonance image
- Ultrasonography
Answer: 1. Computed tomography
Question 10. The principal field arrangements associated with teletherapy is
- Focal field
- Reverse field
- Parallel ipsilateral field
- Parallel opposed field
(Note: Wedged-pair field, parallel-opposed field, and three-field technique are the principal field arrangements associated with teletherapy).
Answer: 3. Parallel ipsilateral field
Oral Cancer Investigation And Treatment Procedures Viva Voce
Question 1. Define carcinoma or tumor.
Answer: Carcinoma is defined as a new growth of tissues or an abnormal mass of tissue, the growth of which is uncontrolled and uncoordinated, exceeds that of normal tissues, and persists in the same manner even after the cessation of stimuli.
Question 2. Compare
(or)
Differentiate benign and malignant tumors.
Answer:
Question 3. How alcohol is increasing the chances of cancer occurrence in tobacco users?
Answer:
- Alcohol causes dehydration of oral mucosal epithelium and increases the penetration of tobacco by-products into the underlying mucosa.
- The liver cirrhosis associated with alcohol reduces the detoxification effect of the liver on carcinogenetic substances.
- Nutritional imbalance and decreased immunity in alcoholics due to reduced appetite and improper diet indirectly increase the risk of cancer.
Question 4. What is palliative care?
Answer:
- Palliative care includes all efforts given for pain relief and psychological support to the patients and their families from diagnosis, through diseases.
- The purpose is to provide quality care for life regardless of the possibility of a cure.
Question 5. What is a sentinel node?
Answer: It is the first lymph node receiving lymphatic drainage from a malignant tumor.
Question 6. What is IMRT?
Answer:
- Intensity-modulated radiation therapy is called as IMRT. It uses a computer-aided radiation source to target the cancerous tissue more preciously.
- Advantage of IMRT—Maximize the radiation dose to tumor site and significantly reduces the radiation dose on normal structures.
Question 7. Explain about combined therapy in cancer management.
Answer:
- Combined therapy is indicated in patients with advanced stages of a tumor or an aggressive tumor. In this method, the benefit of combining the advantages of radiotherapy and surgery is intended to increase the survival period.
- Surgery—Reduces the tumor size, removes radiation-resistant hypoxic tissues, and removes the bony part of tumor.
- Radiotherapy—Kills the oxygenated peripheral tumor mass, and controls the regional metastasis.
Oral Cancer Investigation And Treatment Procedures Highlights
- Oral cancer, in general, denotes squamous cell carcinoma as it comprises more than 90% of all cancers occurring in the oral cavity. In India, among all type of cancers, oral cancer incidence is 12% in men and 8% in women.
- Early diagnosis and effective treatment of potentially malignant and malignant disorders will significantly reduce the rate of morbidity and mortality. This task exclusively depends on the precise knowledge and investigative skill of dental practitioners.
Leave a Reply