Pet Scans and Breast Cancer

Positron Emission Tomography is an important procedure in breast cancer treatment. According to the American Cancer Society, breast cancer is the second most common cancer among women, behind skin cancer, with an estimated 215,900 new cases of invasive breast cancer to occur among women in the Untied States of America during 2004. Breast cancer is also a phenomenon that affects men, although usually only in rare instances. Although the death rate of breast cancer has declined in recent years due to early detection and improved medical treatment, it is still the second leading cause of cancer-related death in women and the American Cancer Society predicts that approximately 40,110 deaths will result in 2004 from breast cancer.

About Breast Cancer

Breast cancer is the second most common cancer among women and it is estimated that one in eight women in the United States will develop breast cancer in their lifetime. Breast cancer is also a condition that affects men, although only in rare instances. Breast cancer occurs when breast cells become abnormal and form more cells in an uncontrolled manner. A tumor, which is a mass of tissue, develops out of these extra cells and can either be benign (non-cancerous) or malignant (cancerous). 99% of all breast cancer cases are carcinomas (malignant tumors that grow out of surface tissue) and there are two major groups of breast cancer:

  • Non-invasive carcinoma:
    Breast cancer cases in which cancerous cells are confined within a duct or lobule and therefore the cancer cells do not penetrate surrounding tissues. Examples of non-invasive carcinoma are lobular carcinoma in situ (LCIS) and ductal carcinoma in situ (DCIS), which is often considered a potential marker for the development of invasive carcinoma.
  • Invasive carcinoma:
    Breast cancer cases in which cancerous cells grow through the basement membrane that surrounds lobules or ducts and can spread into the supporting tissue (stroma) between the blood vessels, ducts, lymphatic vessels, and nerves. Approximately 95% of all breast cancer cases are forms of invasive carcinoma and includes a variety of cancer sub-types such as tubular cancers, medullary cancers, and mucinous cancers.

Currently, the cause of breast cancer is unknown. However, medical studies have identified a variety of conditions that increase the odds of breast cancer susceptibility:

  • Age:
    Most breast cancer occurs in women over the age of 50, and there is an increased susceptibility to breast cancer for women who experience menopause after the age of 55.
  • Family History:
    Breast cancer susceptibility increases if an immediate family or other close relatives like cousins have a history of breast cancer, particularly at a young age.
  • Breast density:
    Breast cancer risk increases in women who are 45 years of age or older that have mammograms that show at least 75% dense breast tissue.
  • Personal Health History:
    Women who have had breast cancer have an increased susceptibility to another case of breast cancer.
  • Radiation Exposure:
    Women whose breasts had been exposed to radiation during childhood, particularly those who had been treated with radiation for Hodgkin’s disease, are at an increased risk to breast cancer.
  • Estrogen Exposure:
    Breast cancer risk is often affected by the amount of time a woman’s body has been exposed to estrogen during their lifetime. Women who had started menstruated at the age of 12 or earlier have a slightly increased risk to breast cancer as do women who experience menopause after the age of 55 as well as women who have taken hormone replacement therapy for longer than 5 years.
  • Childbearing:
    Women who have their first child after the age of 30 or women who have no children are at a slightly increased risk of developing breast cancer.
Symptoms of Breast Cancer

Regardless of the type of breast cancer, the PET scan is an important tool that can be used to reverse its effects. As the cause of breast cancer is still unknown, early detection of breast cancer is instrumental in breast cancer treatment. Breast cancer usually first becomes evident as a lump on the breast or a spot that is evident on a mammogram. In order to detect breast cancer in its early stages, the American Cancer Society recommends these actions:

  • For women between the ages of 20 and 39, it is recommended that a physician or another qualified health care practitioner perform a clinical breast examination every 3 years.
  • For women who are 40 or order, it is recommended that a physician or another qualified health care practitioner perform a clinical breast examination and mammogram annually.
  • For pre-menopausal women, it is recommended that they perform a breast self-examination every month, usually in the week after their period ends.
  • For post-menopausal women, it is recommended that they perform a breast self-examination every month, by picking a particular date each month for it to be performed.
  • Screening mammograms should be performed regularly and for women who are 40 or older, it should be performed annually. Mammograms are a special kind of x-ray that is designed to examine breast changes in women who have no signs of breast cancer.

Despite the many varied ways available for breast cancer detection, breast cancer is a condition that usually has no symptoms associated with its early stages. Usually symptoms become present at a later stage and often these symptoms do not indicate cancer. However, if any of these symptoms are present, it is highly recommended that a qualified doctor be notified for their diagnosis:

  • The presence of a lump in the breast or underarm area
  • Swelling or thickening in the breast or underarm area
  • Changes in the size or shape of the breast
  • Ridges or pitting of the breast in which breast skin looks like an orange peel
  • Nipple discharge or tenderness
  • Nipple bleeding
  • Nipple inversion, in which it is pulled back into the breast
  • Changes in the look or feel of breast skin, areola, or nipple

In advanced cases of breast cancer, symptoms may also include:

  • Bone or back pain
  • Breathing difficulty
  • Presence of swollen lymph nodes underneath the arm
PET and Breast Cancer Diagnosis

Positron Emission Tomography is an effective procedure used in the diagnosis and treatment of breast cancer in the various medical stages of treatment. PET scans for breast are one of the most effective imaging tools in diagnosing breast cancer. As breast cancer has very little symptoms in its early stages, it is usually detected by mammograms. Mammograms are specialized x-rays that takes pictures of breasts as they are pressed between two plates. Very low levels of radiation are used in a mammogram and they are effective in detecting the presence of tumors.

However, mammograms are a form of anatomical imaging and is consequently limited as it is only able to detect physical change in the breasts. Positron Emission Tomography is a procedure that is able to detect whether or not an abnormality detected by a mammogram is benign (alive tissue and non-cancerous) or malignant (dead tissue and cancerous). Although PET imaging is not widely used in breast cancer treatment, recent medical studies have shown that in the future, PET scans may be a useful tool used in conjunction with mammograms to detect breast cancer while it is in its early stages. A recent report conducted by the Clinical Positron Imaging Journal showed that PET scanning had a 94% accuracy rating in detecting breast cancer compared to the 44% accuracy rating of mammography.

PET scans are a noninvasive method that involves the administration of a radioactive tracer that combines a radioisotope (a radioactive compound whose movements are detectable by a PET scanner) with a natural body compound. In breast cancer diagnosis, the radioactive tracer used in the Positron Emission Tomography procedure is Fluorodeoxyglucose (FDG), which combines the natural body compound glucose with the radioisotope Fluorine-18. This radioactive tracer, or radiopharmaceutical, is used in breast cancer detection as the radioactive compound that it uses has a short half-life and will disappear from the body within hours. Therefore, breast PET scans are safe and patients should free themselves of any worry about the radiation content of this procedure.

Additionally, breast cancer PET scans use FDG as it contains the body compound glucose. The use of FDG, which shares a similar structure to glucose, is important, as the absorption of glucose is effective in determining whether a cell is healthy or cancerous. PET imaging traces the absorption rate of FDG by cells and can determine whether cancerous cells are present in the breast and other organs or tissues, as glucose (which FDG shares a similar structure) is absorbed at a faster rate by cancerous cells compared to healthy cells. By tracing the movement of FDG in a patient’s organ, the physician is able to determine whether the breast mass detected through anatomic imaging is benign (non-cancerous) or malignant (cancerous). From the images produced by the PET scan, a physician will be able to make an informed diagnosis, as these images are able to show whether the breast is normal and healthy or if there is the presence of breast cancer.

Early breast cancer diagnosis is instrumental in recovering from breast cancer. Although breast cancer cells are able to travel to all parts of the human body, it usually spreads into lymph nodes in the armpit, chest, and collarbone area. If breast cancer is detected and treated prior to cancerous cells spreading into lymph nodes, the five-year survival rate of breast cancer treatment is approximately 98%.

PET and Breast Cancer Staging

Besides detection, PET scans are effective in the treatment of breast cancer when it is used during the staging phase. Staging commences following breast cancer diagnosis and is used to determine if or how much the breast cancer has spread. The staging component of breast cancer treatment is critical as it provides the necessary information for physicians in determining an appropriate medical course of breast cancer treatment.

Through PET imaging, a physician is able to determine whether or not cancerous cells have spread from the breasts to other parts of the body. Positron Emission Tomography involves the administration of a radioactive tracer that combines a radioisotope, a radioactive compound that is detected by a PET scanner, with a natural body compound, which the body is able to integrate into its system without any negative effects. In PET breast cancer staging, the radioactive tracer used is Fluorodeoxyglucose (FDG) that combines the natural body compound glucose with the radioisotope Fluorine-18. Although many patients have concerns about the radioactive component contained in PET imaging, Fluorine-18 contains a short half-life and disappears from the body within hours. Consequently, the PET procedure is a safe one for patients.

In the staging process, PET scans are the most effective imaging tool in determining the spread of cancerous cells. Other breast cancer staging tests such as mammograms, body scans, and biopsies are either limited in their ability to detect only changes in the anatomical structure of the breasts or are invasive treatments. Positron Emission Tomography, however, is a non-invasive procedure that determines cancer spread more comprehensively and less painfully than these other screening procedures, as it detects biochemistry changes among organs and tissues. By tracing the spread of FDG in a patient’s body, PET imaging is able to establish patterns of cancer spread based on the body’s chemical reactions to FDG. As it is similar in structure to glucose, PET determines cancer spread by studying the absorption of FDG by the patient’s organs and tissues. FDG is absorbed at a faster rate by cancerous organs and tissues than healthy organs and tissues. By studying the biochemical reaction of the patient’s body, PET scan is able to produce the most accurate analysis of whether breast cancer has spread to other areas of the body.

This information is critical in determining an accurate outlook of patient recovery as the early detection and treatment of breast cancer has an extremely high survival rate. For example, through a PET scan, a physician is able to view whether cancerous cells have spread to lymph nodes or other organs. If this is not the case and surgery has been undertaken, the five-year survival rate of this surgery will increase to approximately 98%.

Further breast cancer treatment will be determined by both the type of cancer cells found as well as the stage that the cancer is in. Staging is a vital step in the patient’s road to health recovery, as future breast cancer treatment options are contingent on the size of the cancerous tumor, the spread of cancerous cells, and the location of the cancerous tumor. A PET scan is the most effective lung cancer staging tool and is a vital tool used by physicians in providing a specialized, medical plan to eradicate breast cancer from the patient.

In cases where PET imaging has shown that cancerous tumors are located in an appropriate location within the breast, surgery is often the best option. Surgery can cure breast cancer but its use depends on such variables as its location on the breast, the size of the tumor, and at what stage the breast cancer is. Other medical treatments to breast cancer includes: chemotherapy, which uses drugs to effectively treat breast cancer; hormone therapy, which uses drugs to block estrogen and therefore slow cancerous growth; radiation, which uses X-rays to prevent cancer spread by killing cancer cells; and bone marrow transplant, which replaces a diseased or damaged bone marrow with a healthy marrow.

PET and Breast Cancer Follow-Up

Another valuable function of Positron Emission Tomography in breast cancer treatment is its role in studying the patient’s recovery. Following staging, a physician will recommend a medical course of action that they feel are the most appropriate and effective. In most instances, chemotherapy, radiation therapy, surgery, or a combination of two of the three options is used to treat lung cancer. Although these treatments are usually effective, an important component of breast cancer treatment is determining whether active cancer cells have remained in the body following treatment.

Prior to the clinical use of PET scan, physicians applied radiation therapy and chemotherapy according to standard rules. However, with PET imaging, it is now possible for physicians to specifically cater breast cancer treatments to your particular situation. This is because Positron Emission Tomography allows a physician to view the location, extent, and resilience of a patient’s breast cancer.

Additionally, PET imaging is the most effective diagnostic tool in detecting breast tumor response to therapy. PET scans study the chemical function of the breast and other organs and tissues and is able to produce images that show visual biochemical changes in the body caused by breast cancer. Unlike anatomic forms of imaging such as mammography that details changes in body structure such as the presence of tumors, PET imaging is able to determine whether a tumor is benign (alive tissue and non-cancerous) or malignant (dead tissue and cancerous).

PET scans involve the administration of the radioactive tracer, Fluorodeoxyglucose (FDG) that combines the natural body compound glucose with the radioisotope Fluorine-18. FDG safely travels through the body where a PET scanner monitors its movement within the body. A radioactive tracer that disappears from the body within hours, FDG is able to detect cancer recurrence in successfully treated lesions as well as determine whether tumors identified in an anatomic imaging scan are cancerous or not.

This is because FDG is similar in structure to glucose, which cancerous cells absorb at a faster rate than healthy cells. By tracing the absorption rates of FDG by the targeted cells, a physician is able to determine whether successfully treated lesions are showing signs of cancer recurrence. Additionally, PET imaging is able to detect cancer recurrence in lymph nodes and/or scar tissue from surgery from surgery or another lesion sooner than an anatomical imaging procedure. PET scans are also able to distinguish between cancerous and non-cancerous tumors that are detected by anatomical imaging and are still present despite breast cancer treatment.

In a 2002 article published in the Journal of Nuclear Medicine, it was found that PET scans performed two important functions better than conventional imaging tests for breast cancer treatment. In this study, conventional imaging tests included x-rays, mammograms, ultrasound, computerized tomograpghy (CT), magnetic resonance imaging (MRI), and bone scans. It was determined that PET scans were more effective in detecting early signs of active cancer with an accuracy rating of 93% compared to conventional imaging tests’ accuracy rating of 78%. Additionally, PET scans were shown to be more reliable than conventional imaging tests, with reports showing 16% false positives compared to the 34% false positives shown by conventional imaging tests.

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