PET - Positron Emission Tomography scan is a non-invasive test that aids in imaging the cellular functions and body tissues. It helps in observing the blood flow, oxygen use, and glucose metabolism. A PET scan is of immense help in the diagnosis of cancer, heart disease and brain disorders. The PET scan has been of particular help in the diagnosis of brain tumors, head and neck cancer and esophageal cancer. Since the PET scan reveals metabolic changes in the cells, it aids in early detection of certain conditions such as epilepsy. A PET scan involves injection of a small amount of radioactive tracer drug such as FDG-18. After an hour when the radioactive tracer has spread to the body, the scan is taken. The tracer emits tiny positively charged particles (positrons) that produce signals. A PET scan produces three-dimensional color images from the images taken by a camera that records the tracer as it travels through the body. It is often combined with a CT scan to study a particular body area. Lactating mothers must not breast feed their babies for a few hours after the PET scan.
Salivary Gland Cancer
There are hundreds of minor salivary glands lining parts of the mouth and larynx and can be seen only though a microscope. Many of the salivary gland tumors are non cancerous and they do not spread to other tissues. Salivary gland cancer is a type of head and neck cancer. Advancing age, radiation therapy to head and neck and exposure to cancer-causing chemicals at work are largely factors that cause salivary gland cancer.
Causes and risk factors
Risk of getting salivary gland cancer increases as one gets older. Most develop it in their 50s and 60s. A person is at higher risk of developing salivary gland cancer if exposed to radiation. One may also come in contact with radioactive substances through work. In case of childhood cancer and treatment with radiotherapy, there is increased risk for at least 20 years post treatment. Skin cancer in the past also slightly increases the risk of cancer of salivary glands. Smoking tobacco tends to increase the risk. Human papilloma virus has been noticed in some types of salivary cancer and efforts are on to confirm this. Investigation into the low level radiation from mobile phones is also being done.
Signs and symptoms
While salivary gland cancer may not cause any symptoms, it is sometimes found during a regular dental check up. As symptoms caused by salivary gland cancer may also be caused by other conditions, consult a doctor if any of the following problems occur:
- A painless lump in the area of the ear, cheek, jaw, lip or inside the mouth
- Fluid draining from the ear
- Numbness in the face
- Weakness in the face
- Persistent pain in the face
- Trouble swallowing or opening the mouth wide.
CT and MRI are used to determine if salivary gland cancer has spread to other tissues. An examination of the patient to check signs of health, in the neck, mouth and throat areas is vital. History of patient's health, habits and past illnesses and treatments is recorded. A small amount of glucose is injected into the vein and the PET (Positron Emission Tomography) scanner rotates around the body and takes images where glucose is used in the body. Malignant cells show up brighter in the picture because they are more active and take up more glucose than normal cells do. Endoscopy and biopsy are also done to test for salivary gland cancer. As salivary gland cancer is hard to diagnose, it is recommended to have tissue samples checked by a pathologist who has expertise in diagnosing salivary gland cancer.
Treating salivary gland cancer
Stage I is when cancer is confined to the salivary glands and is 2 cm or smaller; Stage II is larger than 2 cm but not larger than 4 cm; stage III is when it has spread to a lymph node or to soft tissues around the affected gland and stage IV has spread further.
There are three types of standard treatment used for salivary gland cancer – surgery, radiation therapy and chemotherapy. Some may receive more than one type of treatment. Therapy depends upon the stage the patient is in and the higher the stage, more the therapy and aggressive and multiple therapies are given.
If the tumor is small and located in an easy-to-access spot, surgeon may remove it and a small portion of healthy tissue that surrounds it. Removing the entire salivary gland is done if the tumor is large and if the cancer extends to nearby structures such as facial nerves, ducts that connect to salivary glands, facial bones and skin may also be removed.
If the cancer has spread to lymph nodes in the neck, the surgeon may remove most of the lymph nodes. Reconstructive surgery is done by a plastic surgeon to improve the ability to chew, swallow, speak and breathe after the surgery. The patient may need grafts of skin, tissue or nerves from other parts of the body to rebuild areas in the mouth, throat and jaw.
Radiation therapy using neutrons which are more effective in treating certain salivary gland cancers is used. Post surgery, this therapy is used to kill cancer cells that might still remain. In case surgery is not possible and tumor is large and located in a place that makes removal too risky, radiation alone is used to treat salivary gland cancer.
Although this is not currently used as a standard treatment for salivary gland cancer, Chemotherapy is a drug treatment used to kill cancer cells. This may be an option for people with advanced salivary gland cancer that has spread to distant areas in the body.
Those who undergo radiation therapy to the head and neck often experience dry mouth which can be uncomfortable. This can lead to frequent infections in the mouth, cavities and pose problems in teeth and difficulty eating, swallowing and speaking. If such complications arise then:
- Brush teeth several times a day.
- Rinse mouth with warm salt water after each meal.
- Keep mouth moistened with water or sugarless candies.
- Choose moist food and moisten dry food with sauce, gravy, broth, butter or milk.
- Avoid acidic or spicy foods and drinks, such as caffeinated and alcoholic beverages.
The word 'sarcoma' is derived from the Greek word for 'fleshy'. Sarcomas arise from Mesenchymal tissue which is the precursor to fibrous tissue, muscle, bone and fat. Bone sarcoma is malignant tumor or cancer of the bone. The difference between the terms sarcoma and carcinoma is that while sarcomas spread through blood, carcinomas through lymph fluid to the nearby lymph nodes.
Symptoms of bone sarcoma
- Pain in the bones.
- Pain may worsen in the nights.
- Swelling, redness and tenderness at the site of bone pain.
- Swelling of the leg or arm in longer bones such as above or below the knee or upper arm, shoulder etc.
- Bone fracture after a routine movement – like throwing a ball.
- As cancer weakens bones, broken bones tend to occur more easily.
- Fatigue, fever and weight loss and anemia are other signs.
Causes of bone sarcoma
The cause is unknown in most cases although bone sarcoma can develop from benign lesions in the bone and areas that previously received radiation. Therefore persons who received radiation therapy or chemotherapy can be at increased risk. A genetic syndrome called Li Fraumeni and retinoblastoma and a disease called Paget's Disease are also associated with sarcoma.
Types of bone sarcoma
1. Osteosarcoma that occurs in the bones around the knee and upper arm.
2. Chondrosarcoma that begins at the cartilage and ends of bones and lines of joints and in pelvis, upper leg and shoulder.
3. The Ewing sarcoma family of tumors that occurs in bone but may also be present in the connective tissues located in the pelvis, legs and arms.
4. Multiple Myeloma which is a cancer of plasma cells that originates in bones.
Bone sarcoma diagnosis
A doctor examines the patient physically after ascertaining family medical history. Then the physician may recommend the following diagnostic tests:
- X rays in various parts of the body to show location, size and shape of bone tumor.
- Bone scans
- CT scans which reveal cross sectional images to check if the tumor has spread.
- MRI scans
- PET scans that image the body's metabolic action to show if cancer has spread.
Treating Bone Sarcoma
Surgery plays a primary role in the treatment of bone sarcoma. The goal of surgery is twofold. On the one hand it can remove the cancerous tumors and restore the physical function and appearance. On the other hand, a cuff of normal tissue is taken from around the tumor cells to minimize the risk of tumor recurring at the local resection site.
After surgery, the reconstructive or plastic surgery team performs the delicate task of replacing bone. Musculoskeletal oncologists and reconstructive plastic surgeons use donor bone, the patient's own bone from other sites and metal implants to reconstruct limbs and restore function.
Radiation therapy: This can be performed before or after surgery or even during surgery though the use of brachytherapy. Radiation therapy is used to treat tumors or when there is disease recurrence at the site of the original tumor or other localized site. This is especially used in treating chondrosarcomas more often than bone sarcomas.
Chemotherapy: Chemotherapy is given before surgery in order to shrink the tumor and allow for better resection. Surgery and radiation can only act on a small area tumor site. Chemotherapy kills any cancer cells floating undetected elsewhere in the body.
Follow-up depends upon the grade and type of bone sarcoma. In case of Osteosarcoma and Chondrosarcoma, follow-up includes physical exam, chest x-ray which should be performed every three months for at least two years initially and then after four months for a year and then every six months for two years and subsequently annually.