Use of PET/CT in Oncology

Cancer describes a condition where the cells of the body begin to change and multiply chaotically. The extra cells form growths or tumors, which may be benign or malignant. Benign tumors are not cancerous: they can be removed and generally do not return. Malignant tumors, however, are cancer. They not only grow locally, invading and destroying tissues surrounding them, but cancerous cells can break away from the original tumor and start new cancerous growth in other parts of the body. When this occurs, it is called "metastasis."

In early stages, cancers of many kinds can be successfully treated and the individuals who have them cured. The challenge is to find cancer early. It often spreads secretly and quietly with no discernible symptoms, evading detection until it presents a much more serious health risk.

Just the word cancer evokes a certain amount of fear in many people. Cancer comes in a variety of different forms and affects millions of Americans each year. The American Cancer Society estimates nearly 1.5 million cancer cases occur annually. It impacts the lives of many more than that, when family members and caregivers are added in. Fortunately, progress continues to be made both in diagnosing cancer and in treating it.

PET/CT scanning is used in the diagnosis of, and evaluation of treatment for, the types of cancer listed above as well as many other types of cancer, including ovarian cancer and cervical cancer, as well as bladder and kidney cancer.

Topics:

Breast Cancer | Colorectal Cancer | Esophageal Cancer | Head & Neck Cancer

Lung Cancer | Lymphoma | Melanoma | Prostate Cancer | Thyroid Cancer

Breast cancer primarily affects women. Outside of skin cancer, it’s the most frequent cancer that women are diagnosed with. Breast cancer can occur in men as well, but for men it is quite rare. Significant strides have been made in diagnosing and treating breast cancer over the past few years, and the good news is that the death rate for women with this disease is declining, though it still poses a serious health risk.

Early diagnosis of breast cancer is critical. If found and treated before it has spread elsewhere in the body, the five-year survival rate is over 90%. But early diagnosis of breast cancer remains a challenge. Most often it is discovered and confirmed through physical examination, mammography, ultrasound or fine needle aspiration.

A PET/CT scan can show whether a lump in the breast is benign or malignant, often without the expense and ordeal of a breast biopsy. If there is malignancy, PET/CT can detect if there is distant metastasis (i.e. whether the cancer has spread), determine what other parts of the body are affected, and provide information that will result in more accurate staging and treatment of the disease. Breast cancer can spread to nearly anywhere in the body, but most commonly it spreads to the brain, bone, and liver.

The type of treatment that will take place -- surgery, radiation therapy and/or chemotherapy -- will be decided upon largely based on information from the PET/CT scan, currently the most accurate method for finding localized or distant disease. PET/CT scans are also used to evaluate the effectiveness of different types of treatment.

Even after successful treatment, breast cancer patients must be monitored to make sure the disease has not recurred. PET/CT scans are often part of that monitoring process.

Colorectal cancer is the third most common cancer for both men and in women. Detection and treatment of colorectal cancer has improved over recent years, and mortality rates continue to decline. As with most cancers, early diagnosis is the most important factor in a successful treatment and outcome.

PET/CT scans are the most useful diagnostic tests for staging or re-staging colon or rectal cancer. Once the disease is staged, a treatment plan will be developed that may include surgery, radiation therapy, and/or chemotherapy.

If the cancer has remained localized to the colon area, surgery to remove it is the most common form of treatment. Even if the cancer has spread in a limited way – surgery may be able to remove those additional tumors and eliminate most of the cancerous material. During or subsequent to treatment, follow-up PET/CT scans help to determine how successful treatment has been in eliminating the cancer.

Following treatment for colorectal cancer, the patient will need periodic follow-ups for several years. Physical examination, colonoscopy and blood tests will be used. Imaging with PET/CT is also important to assess whether cancer has returned. The good news for colorectal cancer patients is that most who live five years without a recurrence can be considered cured; it rarely recurs after that period of time.

The esophagus is the muscular passageway connecting the throat to the stomach. Early detection of cancer in the esophagus can be difficult because the individual often has no symptoms, and there are presently no screening tests to detect it. When the individual does become aware of it -- the most frequent symptom being difficulty in swallowing as cancerous tissue narrows the diameter of the esophagus -- it is often already at an advanced stage.

As with other forms of cancer, the treatment and prognosis for the individual with esophageal cancer depends on the stage of the cancer. An initial PET/CT scan will help to assess the location and extent of the cancer.

Many types of treatment for esophageal cancer cause significant side effects and sometimes a mass remains in the esophagus even after treatment is concluded. Periodic visits during and following treatment will be needed for your physician to help you manage the side effects and also to monitor the effectiveness of the treatment that’s been provided.

With esophageal cancer, follow-up imaging with PET/CT is important to monitor whether or not cancer has returned in the treated regions. If it recurs, a new treatment plan will be required.

"Head and neck cancer" describes a variety of types of malignant tumors that can occur in the mouth, throat, sinuses, larynx, salivary glands, thyroid gland, and cervical lymph nodes. (Brain tumors are usually not considered to be a part of this particular category of cancers.) Symptoms may include a sore or lump on or in the mouth or throat that doesn’t heal, a sore throat, an unexplained change in the voice, or bleeding, pain or numbness in the mouth. Like many cancers, malignant head and neck tumors can then spread – often doing so through the lymph nodes in the neck.

Head and neck cancers represent only 5 percent of all cancers diagnosed, but they can be especially devastating because of their location in the body. Treatment can result in decreased or lost functionality in the treated area. The earlier the cancer is identified and diagnosed, the less invasive the required treatment may be.

Head and neck cancers are treated through surgery, radiotherapy and/or chemotherapy. It is unfortunately sometimes necessary to remove or treat normal tissue around the tumor as well as the tumor itself.

PET/CT scanning is the most useful test to have in diagnosing and treating head and neck cancer. It is also very valuable in re-staging cancer as it helps the physician know whether new symptoms are a result of the treatment or indicate new growth of the tumor.

Lung cancer is a particularly serious form of cancer because it can grow in the body and spread for a long time before being detected. It accounts for the most cancer-related deaths in both men and women -- more than breast, colon and prostate cancer combined. Early detection is challenging because there are often no symptoms for a very long time. When symptoms do occur they may include chest pain, hoarseness, trouble with breathing, rapid weight loss, a cough that doesn’t go away or a bloody mucous that is expelled when coughing.

PET/CT imaging is very important finding lung cancer as early as possible. While chest x-rays, CT and MRI scanning can determine the size and location of cancer in the lung, PET/CT alone can help identify whether the abnormality is benign or malignant – often eliminating the need for biopsy. This is particularly beneficial for patients who are not good candidates for biopsy, because of the current state of their health or the way the mass is situated within their body. It also provides the most accurate information for staging the disease (assessing its progress) and determining whether cancer is operable or inoperable.

There are two primary types of lung cancer: small cell lung cancer (SCLC), and the more common non-small cell lung cancer (NSCLC). Small cell lung cancer is characterized by small cancer cells that accumulate rapidly into large tumors and then often travel to lymph nodes, liver, brain and/or bones. PET/CT scans are not used with SCLC because the treatment for this disease does not change based on the location of the cancer. PET/CT scanning is very useful for non-small cell lung cancer, which includes a variety of sub-categories of lung cancer. These include squamous cell, adenocarcinoma, and large-cell lung cancer. All of them are capable of quickly spreading to other parts of the body.

Once lung cancer is diagnosed and assessed, a treatment plan will be developed. If the cancer has not spread too far, then surgery to remove it is done. That surgery may be accompanied by chemotherapy and/or radiation therapy as well. If the cancer has spread, it will most likely be treated by chemotherapy and/or radiation therapy.

During and following treatment, PET/CT scans may be used to assess the effectiveness of the treatment and monitor any recurrence of cancer activity in the body.

Lymph is a fluid that circulates throughout the body providing oxygen and nutrients while also picking up fats, bacteria and other unwanted materials and filtering them out through the lymphatic system, an important part of each person’s immune system. Lymph travels through a network linked by lymph nodes, which act as filters for the unwanted materials and also produce white blood cells called lymphocytes. Lymphoma – cancer in the lymph system - occurs when lymphocytes are in a state of uncontrolled cell growth and multiplication.

There are two types of lymphoma: Hodgkin’s lymphoma (or Hodgkin’s disease), named for Dr. Thomas Hodgkin who identified it in 1832, and non-Hodgkin’s lymphoma (NHL). In both, the lymph nodes become enlarged and cancer can spread through the body via the lymph system. Doctors determine which form of lymphoma a patient has by looking at the cancer cells under a microscope. There are no screening tests to find Hodgkin's disease or NHL early, and the symptoms of lymphoma can vary highly depending on the area of the body that is impacted. Some people with the disease have no symptoms at all.

A PET/CT scan is a very important tool in diagnosing and staging lymphoma. Before a treatment plan can be developed, doctors must know how much lymphoma exists in the body. The type of treatment that then takes place depends on the type of lymphoma and its staging (how much cancer and where it’s spread throughout the body). A whole body PET/CT scan may be used to detect extra nodal sites of disease such as liver, spleen and bone marrow.

Substantial progress has been made in the treatment of lymphoma over the last quarter century. Surgery, chemotherapy and radiotherapy may be used in treatment. During treatment, follow-up PET/CT scans help to determine how successful the treatment is working to eliminate the cancer. After treatment, PET/CT scans help to monitor the patient to see if the cancer cells have returned. There is evidence that PET/CT scans may also help to identify lymphoma patients who are more likely to achieve remission.

Skin cancers affect a large number of people and vary in the threat they pose to the individual. The American Cancer Society (ACS) estimates that more than a million cases of basal cell or squamous cell cancers occur every year. Most are curable.

The most common serious form of skin cancer is called melanoma, an aggressive skin cancer that can prove fatal. The incidence of malignant melanoma is rapidly increasing, in the U.S. and throughout the world, with sun exposure the underlying factor. The lifetime risk for Americans developing melanoma is currently 1 in 87. Early detection of melanoma is the key to a successful outcome. It’s almost always curable if caught in the early stages, but likely to spread to other parts of the body if it’s not. The high mortality rate of melanoma is due to its ability to spread quickly through the lymphatic and blood systems in the body.

Concerns about skin cancer usually arise from a visual inspection. When a suspected lesion on the skin is detected, it is biopsied (examined under microscope). If it is determined to be melanoma, a surgery will most likely take place to remove it, often removing along with it the surrounding lymph nodes. If there is reason to suspect metastatic melanoma (melanoma that has spread to other parts of the body), a PET/CT scan is very useful in the staging or re-staging of the cancer to determine the best treatment for the patient.

A whole body PET/CT scan is preferred to accurately stage patients with suspected or recurrent melanoma. This helps to get an accurate diagnosis and form an optimal treatment plan.

Prostate cancer is the most common cancer among men (after skin cancer), and it can often be treated successfully. In 2023, an estimated 288,300 men in the United States were projected to be diagnosed with prostate cancer. In 2020, approximately 1,414,259 individuals globally were diagnosed with prostate cancer, making it the fourth most diagnosed cancer worldwide.

The diagnosis and treatment of Prostate Cancer is more accurate and more precise now than ever before because of recent breakthroughs in diagnosis, treatment, and medical imaging. PSMA PET/CT scanning is being used in the detection and treatment management of prostate cancer. PSMA, an acronym for prostate-specific membrane antigen, is the focus of a PSMA PET/CT examination. This protein is discernible on the surface of prostate cancer cells, serving as a marker for visualizing these malignant cells within patients.

Typically, high-risk patients who have undergone prior prostate cancer treatment and exhibit an escalating PSA level of unknown origin are candidates for PSMA PET/CT scans. PSMA PET/CT scans will be ordered by healthcare teams for various purposes, including prostate cancer staging, restaging, treatment planning, and monitoring.

PSA and PSMA, both aid in gauging the potential presence of prostate cancer, but they do so through distinct means. The PSA test involves a blood examination to screen for PSA proteins produced within the prostate gland, whereas PSMA is a protein biomarker situated on the exterior of prostate cancer cells.

PET/CT scans using newer radiopharmaceuticals (tracers) have been found to be better at detecting prostate cancer cells earlier than PET scans done with less specific imaging agents. Research indicates that PSMA PET/CT scans offer significantly enhanced detection of active prostate cancer compared to CT imaging alone, leading to alterations in treatment plans for nearly 50% of patients.

PSMA PET/CT is most often used if it’s not clear if (or exactly where) prostate cancer has spread. For example, one of these tests might be done if the results of a bone scan aren’t clear, or if a man has a rising PSA level after treatment but it’s not clear where the cancer is in the body. PSMA PET/CT scans can also be used to help determine if the cancer can be treated with a radiopharmaceutical that targets PSMA.

During a PSMA PET/CT scan, a radioactive molecule designed to bind specifically to the PSMA protein acts as a tracer. This tracer, combined with a radioactive compound or isotope, aids in identifying areas where it accumulates within the body, thereby pinpointing prostate cancer cells.

Newer tracers that attach to prostate-specific membrane antigen (PSMA) include:

• Ga 68 PSMA-11 (also known as Ga 68 gozetotide, Locametz, and Illuccix)

• 18F-DCFPyl (also known as piflufolastat F 18 or Pylarify)

• 18F-rhPSMA-7.3 (also known as flotufolastat F 18 or Posluma)

Even though some doctors are still learning about the best ways to use these newer types of PSMA PET/CT scans, and these scans might not be available yet in all imaging centers, Adler Imaging has been at the forefront of working with these novel radiopharmaceuticals and has been routinely performing these scans since the first tracer became available in 2021.

According to the American Cancer Society, “For most men with prostate cancer, treatment can remove or destroy the cancer”. Early detection and treatment of most prostate cancers leads to better outcomes and survival rates.

27 million Americans are affected by some form of thyroid disease, more than the number of people with diabetes and cancer combined, according to the American Association of Clinical Endocrinologists. Only a small fraction of these individuals have thyroid cancer.

Thyroid cancer is one of many types of cancer that is difficult to detect early. Symptoms generally don’t appear until the disease has progressed, at which time the individual may notice a lump or bump on the front of the neck, pain in the neck or throat area, enlarged lymph nodes, and possibly difficulty in breathing, swallowing or speaking.

Thyroid cancer affects women disproportionately; about 70% of thyroid cases are diagnosed in females. The prognosis for most thyroid cancer patients is good, but the rate of recurrence is fairly high. About 30% of individuals treated will experience a recurrence of the cancer. Most often it recurs in the neck, but it can come back in other parts of the body, and it can come back years after the initial treatment.

Physicians break thyroid cancer into four primary types: Papillary, Follicular, Medullary and Anaplastic. All four types are curable with proper treatment. As with most cancers, early diagnosis results in the best outcomes.

Radioactive iodine is the most commonly used method of treating and monitoring thyroid cancer. In some cases, however, thyroid cancer cells can over time lose their ability to absorb radioactive iodine. At this point, PET/CT scanning may be used to more accurately stage the thyroid cancer and provide the information needed to develop an effective treatment plan.