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Why cancer patients need so many CT scans?


You may sometimes feel it quite ridiculous when you are asked to have rounds of computed tomography (CT) scans, especially you are sure that you are well, and it just wastes time and resources.

Computed tomography is a useful tool to detect potential diseases and tumors. Even oncologists cannot make prescription before he/she knows what’s a problem with you. CT screening is such an important assistant who does well in detecting and determining your diseases. Patients need to receive CT scans to identify the condition and be monitored during and after the treatment.

Of course, not all cancer patients are suitable for CT examinations, such as breast and thyroid cancers. These cancers are screened mainly using the screening mammography.

Colorectal cancer is taken as an example to illustrate why CT screenings are needed.

1. Determine tumor staging to guide treatment schemes

Everyone knows that colorectal cancer diagnosis should be done with a colonoscopy. However, CT screenings are also very important as well. The colonoscopy can be used only to look at the intestines and cannot see the externality of the intestines. Therefore, an abdominal CT screening is needed to determine whether there is any lymph node metastasis, or liver or peritoneal metastasis.

Patients with colorectal cancer also need to have a chest CT scan because colorectal cancer is easily transferred to the lungs. After colorectal cancer is detected, a lung CT scanning is needed to see whether there is a metastatic lesion on the lungs.

When there is no distant metastasis found in the abdominal and chest screenings, surgery may be feasible to treat cancer patients.

If CT scan results show that the tumor has spread to the liver or lungs, it develops into stage IV, which is known as advanced cancer. If this is the case, surgery cannot help to radically resect the tumor, and then radiotherapy and chemotherapy will be given to control the tumor in these areas.

Likewise, the detection and staging of other cancer like lung, esophageal, stomach, liver, pancreas, etc. also require rounds of CT examinations. The screening results can help doctors determine the cancer staging and find whether cancer patients can receive radical resection.

2. Monitor the effect of chemotherapy or radiotherapy

If the tumor spreads to lymph nodes or other distant organs, an instant surgery cannot remove the whole tumor and cancer patients will be given chemotherapy or radiotherapy as adjuvant treatment. After several cycles of chemotherapy, CT scans will be given to see whether the tumor has shrunk.

If chemotherapy shows good therapeutic effects, cancer patients may have a chance to receive surgery. However, if the chemotherapy does not work or tumor cells have become resistant to the drugs, cancer patients will be treated with a new chemotherapy regimen.

3. Detect cancer recurrence after surgery

Cancer can recur and metastasize, even after surgery, therefore continued monitoring is necessary. Take colorectal cancer as an example, the risk for colorectal cancer is highest during the first two years after surgery. Cancer patients shall receive a CT scan to see whether the tumor comes back every three months, as well as every six months in the subsequent next three years. When the tumor does not recur or metastasize in the five years after surgery, cancer patients are called cured in the medical domain, for they are less likely to get a tumor recurrence later.

Do so many CT scans harm Your body?

When you do CT scans, you are exposed to radiation. If you do CT scans too many times, it may cause harm to the body and even lead to cancer. Therefore, cancer patients should be checked according to the needs of the disease.

The American Society of Radiology holds that individuals can receive a cumulative maximum dose of 100 mSv for normal diagnostic imaging scans in a lifetime. This means adults can receive about 5,000 chest X-rays, 50 head CTs, 66 low-doss chest CTs, 18 chest CTs and 12 abdominal CTs.

Doing so many CT scans may lead to cancer, but cancer patients need to fight cancer rather than prevent cancer, so the benefits that cancer patients get from CT scans outweigh the potential risks.


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