Bone metastasis is the most common site in patients with lung cancer.

Bone metastasis is the most common site in patients with lung cancer. Bone metastasis is the most common metastatic site for lung cancer patients. How to treat and prevent it?

Bone is a common site of lung cancer metastasis, and the incidence of lung cancer bone metastasis is about 10% to 15%. The median survival time of patients with lung cancer bone metastasis is only 6 months to 10 months, and the 1-year survival rate after treatment is only 40%-50%.

Bone-related events (SREs) caused by bone metastases, such as bone pain, pathological fractures, spinal cord compression, hypercalcemia, etc., can significantly shorten the survival time of lung cancer patients. Studies have shown that the survival time can be shortened by half. Therefore, the early detection and early treatment of bone metastases is extremely urgent.

01. Why does lung cancer have bone metastases?

In recent years, the achievements of lung cancer in the field of precision medicine have significantly improved the survival conditions of patients with advanced lung cancer. But the longer a patient with lung cancer lives, the probability of local and distant metastasis of the tumor also increases. Among them, bone is the most common site of distant metastasis of lung cancer.

Bone metastasis is defined as “bone damage caused by malignant tumors that originated from other than bone tissues transferred to bone tissue through blood”. Although bone tissue is hard, it is still an organ and needs blood to supply nutrients. If tumor cells appear in the circulatory system, the tumor cells flow to the bone with the blood, and even if the bone tissue is hard, it cannot avoid metastasis.

02. Two main symptoms of bone metastasis: bone pain and pathological fracture

Although bone metastasis of lung cancer will greatly affect the quality of life and survival time of patients, about half of bone metastases are clinically asymptomatic, which also reminds us of the necessity of regular and comprehensive review.

Among symptomatic bone metastases, bone pain is the most common, followed by pathological fractures. The manifestations of pathological fractures are very similar to those caused by trauma. Some patients have symptoms of spinal cord compression, such as similar to lumbar intervertebral discs. Outstanding performance, discomfort of the lower limbs and even urinary and fecal dysfunction. There may also be manifestations such as increased blood calcium in the blood biochemical examination.

03. Easily transferred parts: spine and trunk bone

The incidence of lung cancer bone metastasis is related to the general location and the pathological type of the primary cancer. Lung adenocarcinoma has the highest incidence of bone metastasis, followed by small cell lung cancer and squamous cell carcinoma.

The most common sites for lung cancer bone metastasis are the spine and the proximal torso. It occurs in 50% of the spine, 25% of the femur, and 12% of the ribs and sternum. I have known a patient who had undergone bone metastasis during the first examination. The main manifestations at that time were leg pain, difficulty walking, and obvious pain in the vertebrae of the neck and trunk.

04. What tests are needed to diagnose bone metastases?

The best diagnosis method is biopsy, and bone metastases are no exception. Secondly, nuclear medicine examinations, imaging and laboratory examinations are included.

1. Bone biopsy:

Pathology is the gold standard for the diagnosis of tumor bone metastases, but not all patients with bone metastases require bone biopsy. If the diagnosis of lung cancer is clear and there are multiple bone destruction lesions throughout the body, bone biopsy is not necessary; if the diagnosis of lung cancer is clear but there are only isolated bone destruction lesions, a biopsy should be actively performed.

2. Radionuclide bone scan (ECT):

It has the advantages of high sensitivity, and the whole body bone tissue is not easy to be missed in one imaging; but other bone lesions other than bone metastases can also have nuclide concentration and show false positives, so ECT is a primary screening method for malignant bone metastases , But not as a basis for the diagnosis of metastatic bone tumors.

3. X-ray scan:

X-ray is a conventional orthopedic examination method, but the sensitivity of X-ray plain film to detect early bone metastases is low, and it is difficult to find early metastases. Plain X-ray film has certain specificity, its operation is simple, the cost is low, and it is still the main auxiliary diagnostic tool for the diagnosis of bone metastasis.

4.CT:

CT is more sensitive than conventional X-ray films in detecting bone metastases, and it is a more practical tool for the diagnosis of bone metastases and the evaluation of bone destruction. It can more accurately show bone destruction and surrounding soft tissue masses; CT is more valuable for patients who are positive for whole-body ECT but negative for plain X-ray, have local symptoms, suspected bone metastases, and MRI contraindications. For early metastasis of cortical bone and bone marrow infiltration, CT diagnosis is less sensitive.

5. PET-CT:

PET-CT can display bone marrow micrometastasis more sensitively and diagnose bone metastases early. PET-CT can simultaneously examine the whole body organs, lymph nodes and soft tissues to comprehensively assess the scope of tumor lesions. PET-CT has special advantages in diagnosing bone metastases and comprehensively assessing tumor conditions, but the examination is expensive.

6. Magnetic resonance examination (MRI):

MRI has high sensitivity and specificity for the diagnosis of bone metastases, and is especially suitable for detecting spinal metastases and patients with neurological symptoms. When bone metastasis is suspected, whole-body bone imaging and X-ray plain film are still uncertain, MRI can be used to provide diagnostic evidence. MRI has a high sensitivity to early metastases in the bone marrow cavity, and is the first choice for evaluating the infiltration of bone metastases in the bone marrow. However, the operation time is longer, which can increase the patient’s pain during the examination for patients with bone-related time.

Laboratory tests are what we usually call blood tests, which indicate that the indicators of bone metastasis include blood calcium levels, alkaline phosphatase levels, etc. However, there are too many abnormal changes in these two indicators, which require professional doctors to combine clinical and clinical studies. Interpretation by other auxiliary examinations. In other words, the increase of a single index does not mean that it is bone metastasis.

05. How to judge that bone metastasis has indeed occurred?

At present, some countries’s expert consensus has two diagnostic criteria for lung cancer bone metastasis:

1. Clear diagnosis of lung cancer + diagnosis of bone biopsy

2. Definite diagnosis of lung cancer + typical imaging findings of bone metastases

In other words, the doctor can confirm whether the patient has bone metastasis based on the above two diagnostic criteria after the above-mentioned examination results.

06. Three methods for treating bone metastases

First of all, we need to be clear that bone metastasis of lung cancer occurs. Whether it is a single bone metastasis or multiple bone metastases throughout the body, it is the advanced stage of lung cancer. The main purpose of treatment is to improve the quality of life, prolong life and relieve symptoms.

The current main treatment methods can be divided into three categories:

The first category is the treatment for tumors, because even the tumor cells that have metastasized to the bone are still lung cancer cells, the treatment for lung cancer can also control bone metastasis. Specific to lung cancer includes targeted therapy, chemotherapy, radiotherapy and immunotherapy.

How to choose between radiotherapy and chemotherapy for bone metastases?

Generally speaking, there is still some bias in the treatment of lung cancer with radiotherapy, because I always feel that the side effects of radiotherapy are large and it is only a local treatment.

First, the lung cancer itself is the primary tumor with simultaneous radiotherapy and chemotherapy; second, the corresponding radiotherapy for metastases, such as radiotherapy from the mediastinum, can effectively alleviate the disease; secondly, if the patient has bone metastases, radiotherapy to the metastatic site It is a pretty good choice.

The second type of treatment is symptomatic treatment, combined with the symptoms of bone metastasis, including analgesic treatment (medicine, intervention, and surgical pain relief), radiotherapy at the site of bone metastasis, radionuclide therapy, and surgical treatment (pathological fractures and spinal cord compression) Fixation), interventional therapy (ablation, osteoplasty, and brachytherapy), bone-modifying drugs (bisphosphonates, denosumab) treatment.

One to three generations of bisphosphonates can be used to treat bone metastases

Lung cancer bone metastases are generally recommended to be treated with one to three generations of bisphosphonates. Zoledronic acid can inhibit osteoclast activity and induce osteoclast apoptosis in vitro. It can also block the absorption of mineralized bone and cartilage by osteoclasts by binding to bone. Zoledronic acid can also inhibit the increase in osteoclast activity and the release of bone calcium induced by a variety of stimulating factors produced by tumors.

Studies have shown that the median time for bisphosphonates to treat bone metastases is 9 months to 18 months, which means that after treatment, the survival time of lung cancer bone metastases has doubled. Therefore, unless the adverse reactions of such drugs cannot be tolerated or contraindications occur, it is recommended that the drug should be continued for at least 9 months, and long-term use should be considered based on the patient’s benefit.

Note: In the process of using zoledronic acid chemotherapy, it is necessary to avoid the use of some nephrotoxic drugs at the same time, including the use of contrast agents for examination, because the contrast agent itself can also cause damage. Generally speaking, if the patient’s creatinine level is still relatively good, it is <3mg/100ml, and there is no need for drug reduction in the absence of increased 24-hour urine protein.

Targeted drug for bone metastasis of lung cancer: Disumab

Disulumab is a bone resorption inhibitor with a unique mechanism of action. It specifically targets nuclear factor kappa B receptor activator ligand (rRANKL), inhibits the activation and development of osteoclasts, reduces bone resorption, and increases bone density .

On November 20, 2020, the new indication of desulumab was approved for marketing in China for the prevention of bone metastasis of solid tumors and bone-related events (SREs) in multiple myeloma, becoming the first and the only approved in China Bone targeted drugs for this indication. Moreover, Disumab has entered the latest version of the medical insurance catalog, and lung cancer patients can use the drug at a low price.

Analgesics

For patients with lung cancer and bone metastases, pain medication should be based on the World Health Organization (WHO) cancer three-step analgesic treatment guidelines. The drug analgesic treatment of patients with lung cancer bone metastasis pain follows the five basic principles of oral administration, step-by-step administration, timely administration, individualized administration and attention to specific details.

The third category is other treatments, including psychotherapy and other content. Once a patient is due to lung cancer and has bone metastases, it means that the patient’s condition has reached the fourth stage of clinical staging. At this time, the confidence of the patient and their families in the recovery of the disease will often fall into a trough. At this time, it is necessary to deal with it from many aspects. In addition to the above-mentioned medical support, patients themselves should also raise their awareness of bone metastases from lung cancer and be prepared for long-term confrontation with such chronic diseases.

07. What should be paid attention to in daily life?

Avoid smoking and alcohol

Excessive alcohol or tobacco reduces calcium, vitamin D and sex hormones, which directly affects the function of bone cells and is not conducive to recovery.

Pay attention to maintaining a balanced nutrition

Insufficient intake of protein, calcium and vitamin D will make bones brittle. Patients with bone metastases are more likely to increase the loss of local nutrients due to the osteolytic destruction of metastases. Appropriate supplementation of nutrients is important for patients with bone metastases.

• Avoid excessive salt intake
• Excessive salt promotes calcium loss and affects bone cell function.
• Appropriate exercise
• Active muscles can stimulate the self-repair of bone tissue.
• Sunshine regularly

80% to 90% of the vitamin D production in the body depends on the skin to receive ultraviolet rays, and the sun is not enough. Vitamin D is an important element to maintain the balance of calcium metabolism in the body, and it can alleviate the calcium metabolism disorder caused by lung cancer bone metastasis.

It is not a miracle that lung cancer bone metastasis is effectively controlled. While cooperating with doctors to check and treat in time, communicate with friends who have similar conditions to find reasonable solutions based on each specific situation.

(source:internet, reference only)

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