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Metastatic Neoplasms 

Metastatic Neoplasms
Chapter:
Metastatic Neoplasms
Author(s):

Dale Bixby

DOI:
10.1093/med/9780190862800.003.0073
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date: 18 September 2020

  1. A. Introduction

    1. a. Detection of malignancies. Malignancies are usually detected in one of three main ways:

      1. i. Screening (e.g., breast, cervical, prostate, and colorectal cancer)

      2. ii. Local symptoms or findings (e.g., pain, change in bowel habits, hematuria, lump or mass)

      3. iii. Systemic symptoms or findings (e.g., metastatic disease, paraneoplastic syndromes, B symptoms)

    2. b. Common sites of metastasis. This chapter will focus on malignancies that commonly metastasize to the bone, brain, liver, and lung. If, after an intensive search, the primary site of the carcinoma is not found, then the term carcinoma of unknown primary (CUP) is used, and treatment is centered on the most likely primary site.

    3. c. Malignancies with variable sites of metastasis. Although many malignancies are capable of metastasizing to different areas, there is a core group that can go anywhere—thyroid cancer, lung cancer, breast cancer, renal cell carcinoma, sarcoma, and melanoma.

  2. B. Metastasis to Bone

    1. a. Common malignancies that metastasize to bone are depicted in Figure 73.1.

      Figure 73.1 Despite the long lists of malignancies capable of metastases in conventional textbooks, the most common cancers that involve the bone, brain, liver, and lungs can practically all be contained in an easy-to-remember, “benzene ring” diagram. The benzene ring represents the human body; the cancers are placed at their approximate anatomic position with melanoma circling the ring (*sarcoma can arise anywhere). Even though this diagram is set up to help you remember those cancers that metastasize to bone, the same diagram (with some slight modifications) can be used to recall the cancers that go to the brain, liver, and lung.

      Figure 73.1 Despite the long lists of malignancies capable of metastases in conventional textbooks, the most common cancers that involve the bone, brain, liver, and lungs can practically all be contained in an easy-to-remember, “benzene ring” diagram. The benzene ring represents the human body; the cancers are placed at their approximate anatomic position with melanoma circling the ring (*sarcoma can arise anywhere). Even though this diagram is set up to help you remember those cancers that metastasize to bone, the same diagram (with some slight modifications) can be used to recall the cancers that go to the brain, liver, and lung.

      1. i. Breast cancer

      2. ii. Prostate cancer

      3. iii. Lung cancer

      4. iv. Thyroid cancer

      5. v. Renal cell carcinoma

      6. vi. Melanoma is included in the diagram between all cancers because it can metastasize anywhere. Melanoma should always be considered when a patient has a metastatic malignancy in any organ.

      7. vii. Sarcoma

      8. viii. Gastrointestinal (GI) cancers

    2. b. Sites of metastasis. The bones most commonly involved are the vertebrae, femur, pelvis, ribs, and sternum (in that order). Bone lesions are classified as osteolytic, osteoblastic, or mixed, and the nature of these lesions may help identify the primary cancer. Some examples are:

      1. i. Osteolytic or lytic bone lesions (renal, thyroid, liver, myeloma) are due to the destruction of normal bone and can be seen on plain radiographs (skeletal surveys) but will not typically show up on bone scans.

      2. ii. Osteoblastic or sclerotic bone lesions (prostate) are due to bone deposition and are identified on bone scans.

      3. iii. Mixed osteolytic and osteoblastic (breast, lung).

    3. c. Symptoms and signs of bone cancer. Cancers that involve the skeletal system can be asymptomatic or produce pain, deformities, pathologic fractures, hypercalcemia, and cord compression (this is an oncologic emergency).

    4. d. Treatment. Along with malignancy-specific therapy, bone metastases can be treated palliatively with local radiation, surgical stabilization, and bisphosphonates, depending on the histology and severity of disease.

  3. C. Metastasis to the Brain

    1. a. Common malignancies that metastasize to the brain. More than 50% of brain tumors are due to metastases.

      1. i. Lung cancer (most common)

      2. ii. Breast cancer

      3. iii. Melanoma (also associated with a high risk for spontaneous bleeding)

      4. iv. Gastrointestinal tract malignancies

      5. v. Renal cell carcinoma

    2. b. Sites of metastasis. Most brain metastases are supratentorial in the gray-white matter border. They can present as a solitary mass or as multiple metastatic deposits.

    3. c. Symptoms and signs of brain metastasis include evidence of increased intracranial pressure and focal or diffuse brain disturbances such as seizure or headache.

    4. d. Treatment. Acute treatment typically involves steroids (dexamethasone), which can effectively improve symptoms and decrease cerebral edema. Consults to radiation oncology to assess for whole-brain or focal irradiation and neurosurgery to determine whether surgical resection or stereotactic radiosurgery is an option are recommended. Treatment depends on the number and distribution of metastases. Systemic chemotherapy can be useful but generally takes time to see benefit.

  4. D. Metastasis to the Liver. Metastatic involvement of the liver is common and can occur with virtually any cancer (except primary brain cancer). In the United States, the incidence of metastatic cancer to the liver is much more common than primary hepatocellular carcinoma. Only cirrhosis causes more cases of fatal liver disease.

    1. a. Common malignancies that metastasize to the liver. The liver is the most common site of visceral metastases from cancers of the GI tract.

      1. i. GI tract malignancies (via portal circulation)

      2. ii. Pancreatic cancer

      3. iii. Breast cancer

      4. iv. Lung cancer

      5. v. Renal cell carcinoma

      6. vi. Prostate cancer

      7. vii. Melanoma

      8. viii. Ovarian and endometrial cancers

      9. ix. Testicular cancer

    2. b. Symptoms and signs of liver metastasis. Often the first (and sometimes only) serum abnormality is an elevated alkaline phosphatase, this is nonspecific and can also occur with bone metastases. Other serum abnormalities include elevated transaminases and hyperbilirubinemia (particularly with obstructive jaundice due to obstruction of the common hepatic duct or common bile duct). Clinically, left upper quadrant pain and palpable hepatomegaly can occur and may lead to further radiographic studies.

    3. c. Treatment. Surgical resection is the only curative option and should only be done if the primary site of disease is also surgically resectable. Systemic chemotherapy is commonly used but rarely curative. Other options include hepatic intra-arterial chemotherapy, percutaneous injection, cryosurgery, and hyperthermic coagulation depending on the size and distribution of lesions. External hepatic radiation therapy is limited by its detrimental effect on normal liver.

      Hot Key

      In patients with isolated elevations of alkaline phosphatase, consider metastatic involvement of the liver.

  5. E. Metastasis to the Lung

    1. a. Common malignancies capable of metastasizing to the lung. Although almost any malignancy can involve the lung, the most common include:

      1. i. Breast cancer

      2. ii. Renal cell carcinoma

      3. iii. Bladder cancer

      4. iv. Gastrointestinal tract malignancies

      5. v. Testicular cancer

      6. vi. Thyroid cancer

      7. vii. Melanoma

      8. viii. Sarcoma

    2. b. Sites of metastasis. Lung metastases are typically located in the peripheral areas of the lung parenchyma and present as round nodules varying in size. Consolidation and cavitation are less common forms of metastatic deposition.

    3. c. Symptoms and signs of lung metastasis. Often patients are asymptomatic, and metastatic disease is found incidentally on surveillance imaging studies or on imaging performed for nonpulmonary reasons. Chest wall or pleuritic pain can occur depending on the sites of involvement. Cough, dyspnea, and hemoptysis can also occur due to direct extension of the mass into the airway. Horner’s syndrome can occur if a lesion involves the sympathetic chain.

    4. d. Treatment. Chemotherapy, radiation, bronchial stenting, and surgery may all be viable options for therapy depending on a number of contributing factors.

Suggested Further Readings

Patchell RA, Tibbs PA, Walsh JW, et al. A randomized trial of surgery in the treatment of single metastases to the brain. N Engl J Med 1990;322:494–500. (Classic Article.)Find this resource:

Ropper AE, Ropper AH. Acute spinal cord compression. N Engl J Med 2017;376:1358–69.Find this resource:

Schwartz RS, Erban JK. Timing of metastasis in breast cancer. N Engl J Med 2017;376:2486–8.Find this resource: