Bone metastases are often only discovered when they cause symptoms. They can manifest themselves, for example, through bone pain. Patients, relatives and interested parties will learn in this text which examination procedures are used to detect bone metastases.
However, information from the Internet cannot replace a medical consultation: Only an examination can show whether bone metastases are actually behind complaints or whether another, more harmless cause is responsible.
Symptoms: Signs of bone metastases
Bone metastases do not initially cause any symptoms.
Symptoms of bone metastases are usually not particularly clear-cut. Back pain or pain in the arms or legs can have other, more harmless causes, even in tumor patients. An indication of metastases is when none of the otherwise usual therapies work within a reasonable period of time.
Bone fractures that cannot be explained in any other way are also cause for a detailed examination of the cause. If bone metastases press on nerves in the arms, legs or on the spinal cord, this can be noticeable through sensory disturbances such as tingling or numbness. In the case of vertebral metastases, paralysis or disturbances of the bladder and intestines are possible due to damage to the spinal cord. An elevated level of calcium in the blood indicates remodeling processes in the bone.
Closer look: What symptoms may indicate bone metastases?
Pain is the most common symptom in bone metastases, but does not occur in every patient. Pain can radiate from the affected skeletal sections to other regions:
- Pain in the neck, often radiating to the shoulders, may indicate metastases in the cervical and upper thoracic spine.
- Low back pain in the lower back may be due to metastases in the lumbar spine.
- Pain in the low back, often less severe when standing than when sitting or lying down, may be a sign of metastases to the sacrum at the base of the spine.
- Hip pain that increases with exertion can be a characteristic of an attack on the upper leg.
Pain occurs when the metastases damage the sensitive nerves of the periosteum. In addition, the remodeling processes in bones lead to a release of messenger substances, for example, inflammatory signals. These also trigger pain.
Hypercalcemia may also indicate bone metastases. It occurs when the calcium level in the blood rises due to remodeling processes in the bone. This can cause dysfunction in almost any organ system in the body. Signs of kidney damage include a strong feeling of thirst, increased urine output and fatigue. Severe hypercalcemia is life-threatening if not treated: Cardiac arrhythmias are possible due to the disruption of mineral balance. Hypercalcemia is comparatively rare. Experts estimate that one to five in 100 patients are affected by bone metastases.
So-called bone marrow carcinoses are also rare. They occur in eight to ten out of 100 patients with bone metastases. Bone marrow carcinosis is when a large number of tumor cells have invaded the bone marrow. This disturbs the blood formation in the bone marrow. If there is a lack of red blood cells (erythrocytes) in the blood as a result, this is called anemia. The result is a poor oxygen supply to the body. Signs can include fatigue, dizziness and shortness of breath. Less frequently, there is a deficiency of white blood cells, which impairs immune function, or of platelets, which are responsible for clotting.
No early detection: routine tests are not generally used
Before the first therapy, patients are examined in detail. How they are treated depends on how far a tumor has spread and whether metastases are already present. In cancers where bone metastases may occur, physicians use appropriate monitoring procedures.
What happens after the end of treatment? Even if those affected are initially considered to be cured, there is still a more or less high risk of relapse, at least in the initial period. In the case of bone metastases, some time may pass between the first cancer diagnosis and the appearance of metastases.
For patients who are also at risk for bone metastases, physicians therefore look for evidence of this during follow-up examinations and ask, for example, about bone and back pain.
If there are specific tumor markers that indicate disease recurrence or metastasis, testing of these markers is also part of follow-up care. This is the case with prostate cancer, for example. Here doctors regularly check the level of prostate-specific antigen (PSA) in the blood. An elevated PSA value can indicate a relapse or the formation of metastases. Then further examinations must clarify what the cause is. However, such specific markers do not exist for all types of cancer. General background on the measurement of tumor markers during follow-up can be found here.
Guidelines make suggestions to help the physician decide for or against a medical measure.
Cancer patients are not regularly screened for skeletal metastases with imaging techniques after treatment is completed. Guidelines for tumor types that frequently develop bone metastases do not include recommendations for targeted routine testing: to date, this has not been shown to prolong long-term survival of affected individuals.
Doctors rely instead on so-called symptom-oriented follow-up care. Imaging procedures are usually only useful when symptoms and complaints or abnormal results from other examinations are present.
Suspicion of metastases: Which examinations should be considered??
If there is a concrete suspicion of bone metastases, doctors clarify this with targeted examinations. Imaging techniques are primarily used. They help to produce images of the inside of the body that are as accurate as possible. The most important question is whether skeletal metastases are actually present. However, signs of tumor metastasis in other organs are also looked for. Other questions are: How stable are affected bones? How far have the metastases already developed?? The answers to these questions help to find an individually adapted treatment. It is not possible to say in general terms which diagnostic technique doctors will use: this depends on the type of tumor and the patient’s symptoms. The procedure chosen is the one that is least stressful and still provides the most accurate information possible. Possible tests include scintigraphy, computed tomography, X-ray, magnetic resonance imaging and PET/CT.
Scintigraphy: marking tumors with radiating particles
Skeletal scintigraphy is a standard procedure for diagnosing bone metastases. It is also used to check the success of treatment for bone metastases.
- In scintigraphy, patients receive low-level radioactive substances injected into the bloodstream. These markers are chemically very similar to calcium, an important component of bone. They accumulate more in bones, which are excessively remodeled.
- Usually the entire skeleton is examined.
A recording device, known as a gamma camera, records the radiation that the body emits. A connected computer calculates images from this. Physicians recognize osteoblastic metastases, in which anabolic processes predominate, particularly well on these so-called scintigrams. However, bone changes such as osteoarthritis, arthritis or inflammation may look similar to metastases on the images. Doctors therefore need further information to evaluate the scintigrams.
Other methods: X-ray, CT, MRI and PET/CT
Further imaging procedures are often necessary for an accurate diagnosis. X-rays, computed tomography and magnetic resonance imaging help to classify initial findings more precisely. They are also useful if the scintigraphy is inconclusive but the suspicion of bone metastases persists. Doctors also use these procedures to monitor how successful treatment is going. The different approaches each have their own merits:
: X-ray equipment is widely used. Examinations can be performed quickly and without great effort. However, they only depict advanced bone destruction. X-rays reveal whether the damage is more likely to have been caused by excessive bone resorption or bone buildup. Doctors use this procedure, for example, when a scintigraphy has yielded suspicious results. Computed tomography is a high-resolution X-ray procedure. Even comparatively small changes can be seen on CT scans. Doctors also use CT to check how far a metastasis has spread into adjacent tissue. The procedure also allows statements to be made about the stability of the bone. (Magnetic resonance imaging, MRI: This diagnostic technique does not work with radiation, but with magnetic fields and radio waves. They are used primarily to examine the spine; for example, the procedure provides details of the spinal cord and spinal nerves that cannot be seen with X-ray procedures. PET/CT is a combination of positron emission tomography (PET) and computer tomography. The images overlay information about the metabolism of cells from the PET with images of the body from the CT scan. In this way, tumor-related metabolic changes can be easily assigned to a tissue or body part. PET/CT can be used to answer similar questions to scintigraphy. While scintigraphy takes pictures of changes in the bone, PET/CT actually offers clues about tumor cell activity. However, the procedure is complex and expensive. In addition, the devices are not available everywhere. Up to now, PET/CT has therefore been more of a complementary method.
CT image of metastases in the vertebral bodies. © Department of Radiology, German Cancer Research Center
Important for patients: No imaging procedure provides one hundred percent reliable results. In the case of so-called "false positives findings, there are other, harmless reasons for the result. "False negatives" Findings, on the other hand, are present when existing bone metastases are not detected. To be on the safe side, experts therefore often use more than one procedure.
A biopsy of the bone is normally only performed if the original, primary tumor is unknown. During a biopsy, doctors remove a sample from the suspicious area. Patients receive a local anesthetic or a short anesthesia. Whether affected individuals need to stay in the hospital longer depends on their situation. For example, if there was a previous bone fracture that needs to be operated on, this can be done in the same procedure.
The tissue samples from the bone are examined by pathologists under the microscope and, if necessary, also with molecular biological methods. The tumor cells contained in the tumor can provide information about the primary tumor if they still show typical characteristics of the original tissue.
Diagnosis of bone metastases: Significance for the course of the disease?
Bone metastases are a sign that a cancer has already progressed. The Cancer Information Service explains in a separate text how these metastases to the skeleton are treated. However, more detailed background information on the influence of bone metastases on the further course of the disease and the prognosis can only be discussed in person with the doctors treating the patient. Information from the Internet cannot replace a consultation with a doctor.