Lymphoma and PET/CT

Lymphoma is classified as either Hodgkin's or non-Hodgkin's lymphoma. In 2002, there will be about 7,000 new cases of Hodgkin's disease and about 53,900 cases of NHL diagnosed, according to the American Cancer Society. The malignant lymphomas are the most common malignant tumors of adults between the ages of 20-40 years. The treatment of lymphoma has been one of the true oncologic success stories of the last 20-30 years. Continued improvements in chemotherapy and radiotherapy have resulted in better survival rates.

There are no screening tests to find Hodgkin's disease or NHL early, and some people with the disease have no symptoms at all. The signs and symptoms of lymphomas may vary depending on the location of the lymph tissue that is involved with the disease.

Because enlarged lymph nodes are the primary sign of lymphoma, it can be difficult to diagnose because enlarged lymph nodes commonly occur when someone has an infection. Doctors often choose to observe swollen nodes over several weeks to look for changes or reductions in size. Some of the most common early symptoms of lymphoma may include the following:

• Enlarged, painless lymph nodes
• Swollen lymph nodes inside the body that create pressure on organs or body parts near them. This can cause such symptoms as coughing, shortness of breath, swelling in the abdomen, intestinal blockage, or abdominal pain.

In addition to the local signs related directly to the enlarged lymph nodes, patients may also experience the following:

• Fever
• Drenching night sweats
• Weight loss
• Itching
• Tiredness
• Decreased appetite

If the suspicious lymph nodes don't heal on their own, a physician will either take a small piece of the node or, more commonly, remove the entire node for examination under the microscope (biopsy).

Proper staging of the location and extent of the tumor is the first step in appropriate treatment. Moreover, once treated, patients are often re-staged to determine the effectiveness of the treatment.

The doctors diagnose the cancer and determine what kind it is by looking at a sample of the tumor under a microscope. This alone does not determine what treatment you should have. Before you are treated, your doctors must determine how much lymphoma you have. This is called staging the cancer.

Treatment options as well as the outlook for your recovery depend on the both on the exact type and the stage of the lymphoma.

Tests used to gather information for staging may include the following:

• A physical examination
• Blood tests
• A bone marrow aspiration and biopsy
• A lumbar puncture (spinal tap)
• Imaging tests including a PET scan

PET is the most useful test that you can have when doctors are staging or re-staging lymphoma because it accurately shows the extent of the spread of the cancer.

Follow-Up

After your treatment, it is important to know if any active cancer cells remain in the body. In the past, the amount and type of therapy used were set according to standard rules. Now, PET allows the type and amount of therapy to be directed specifically to you, the patient, and based on the location and extent of your type of cancer.

Imaging with PET is a critical tool in looking for the return of the cancer. Before PET, it was extremely difficult to monitor patients to see if the lymphoma had returned. Multiple CT scans would be required to capture images of the whole body, and these still could not see the recurrent cancer as sensitively as PET now can. The sooner cancer recurrence is found, the sooner your physician can schedule further treatment or surgically remove it.

PET also can be used to image the response of lymphoma tumors to therapy and to detect whether the cancer might have recurred. After your treatment, PET plays an extremely important role in determining whether the cancer cells have returned. Early studies have shown that PET may also identify patients who are more likely to go into remission and less likely to relapse because PET can reveal a characteristic pattern of reduction in glucose uptake in the abnormal lymph nodes during chemotherapy.

Cancer cells that have been killed by your treatment will not absorb any of the radioactive glucose you are given for the PET scan. In addition, although post-treatment tumor masses may still be present and seen on CT scans, the cancerous cells may, in fact, no longer be alive. Unlike a CT scan, a PET scan can determine this. Conversely, if the cancer cells have come back, PET can see the accumulation of the radioactive glucose much sooner than a CT scan-treatment and your physicians can begin treatment much sooner.

How Does PET/CT make a Difference?

• PET is the most accurate imaging technique available for staging and re-staging patients with lymphoma. In the initial staging, PET provides a baseline for subsequent evaluation of therapy. Whole Body PET may be particularly useful in detecting extra nodal sites of disease such as bone marrow, liver and spleen.
• PET can help doctors selecte a site for biopsy when the first suspected site is not easily accessible.
• Since lymphoma may appear at several sites or be widespread, Whole Body PET scanning is excellent to check for recurrence and to guide therapy effectiveness. PET may be useful following therapy to evaluate patients with persistently enlarged lymph nodes for residual tumor. PET may also identify patients who are more likely to achieve remission and less likely to relapse by showing a decrease in the metabolic activity of abnormal lymph nodes during chemotherapy.

More Information

Academy of Molecular Imaging's World of PET
American Cancer Society
Cure For Lymphoma Foundation
The Leukemia & Lymphoma Society
Lymphoma Research Foundation of America, Inc.
Medline Plus
National Cancer Institute