Osteoporosis: its relation to cancer, diagnosis and treatment

Osteoporosis (OP) is a major global health problem. It is estimated that there are more than 200 million people in the world who suffer from OP and consequently have an increased risk of fractures, the most clinically significant consequence of the disease. Although it is not the only disease of bone metabolism, it is the most common.

It is a disease in which the bone is correctly calcified, but there is less bone per unit volume. In addition, there is an alteration of the bone microarchitecture. That is to say, we find ourselves with a bone that has “less quantity” but is also of “poorer quality”. This leads to a decrease in the bone’s resistance to trauma or load, with the consequent appearance of fractures.

Osteoporosis and cancer

Patients who have suffered cancer, in general, have more risk factors for osteoporosis. Cancer itself can be one of them. Sometimes, during prolonged periods of time, they are immobilized, sedentary, which is one of the main “enemies” for the bone to form correctly, but they also often require treatments (chemotherapy, radiotherapy, corticoids) that directly and indirectly affect the bone in a negative way, preventing its correct formation.

There are some cancers that “feed” on certain hormones, they are “hormone-dependent”, which is why it is necessary to use hormonal therapies, treatments that block or inhibit these hormones, even though this has a negative influence on the correct calcification of the bone. This is the case of hormone therapy for breast or prostate cancer. These treatments reduce the levels of estrogen or the male hormone testosterone (hormones that help maintain bone density) and therefore contribute to the loss of bone mass.

Bone is a living tissue, it is in constant renewal, in constant movement. On the one hand, new bone is formed (bone formation), and, simultaneously, aged bone is destroyed (bone resorption). Osteoporosis appears when the balance between the two is broken, either because the formation of new bone decreases, or because bone resorption increases, or because of both causes simultaneously. Both chemotherapy and radiotherapy act directly and indirectly on this balance, breaking it and favoring the appearance of osteoporosis.

Diagnosis of osteoporosis

After having carried out in the first consultation an anamnesis, an “interrogation” focused on identifying possible existing risk factors, the study is completed in order to obtain a global evaluation of the patient by performing:

  • A blood and urine analysis, which the patient has to collect during 24 hours, to see the circulating levels of calcium, phosphorus in blood and their elimination through urine, as well as determination of other elements that are important for a good formation of bone mass, such as the determination of vitamin D among others.
  • A spine x-ray to see the vertebrae well, that there is none that has decreased in height.
  • Bone densitometry: there are several radiological techniques that allow us to measure the bone mineral density (BMD) of patients. The one we usually use in our daily clinical practice is bone densitometry (DEXA). A bone densitometry is a special X-ray test used to measure the calcium content of bone, usually in the lumbar region and in the hips. It is useful for us to see the BMD at a given time and to assess the evolution of the disease and the response to treatment.
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Treatment of osteoporosis

With all the above, we make a global and individual assessment of the patient, of the bone situation, estimating the risk or not, a priori, of suffering a fracture. Any patient at risk of fracture should be treated regardless of the value of the densitometry. What to treat with? It is an essential combination of general non-pharmacological measures and, in those cases that require it and where indicated, treatment with drugs.

  • General, non-pharmacological, fundamental measures: increase outdoor physical activity, maintain a good intake of dairy products and derivatives in the diet and abstain from toxins (tobacco, alcohol).
  • Pharmacological measures: on the one hand we use drugs that provide calcium and vitamin D supplements and on the other hand, we have drugs that do not provide more calcium or more vitamin D but help these to somehow “fix” better, retain calcium in the bones and also improve the quality of the bones, increase their resistance and reduce the risk of fractures. They act in such a way that the balance we spoke of at the beginning between bone formation and elimination is positive, either by slowing down elimination or increasing formation, or by acting at both levels. Of all of them, today the so-called “bisphosphonates” are still the drugs of first choice.