Purpose or Objective
The aim of the study was to evaluate the effect of detecting new metastases in the liver after SBRT on the life expectancy of patients.
Material and Methods
We analyzed the overall survival rates of 80 patients after SBRT of metastases in the liver and their dependence on various factors. In 41 patients after SBRT, new liver metastases were detected. However, the detection of new metastases alone did not significantly affect life expectancy: the median in these patients was 27 months compared to 31 months in patients without the appearance of new metastases in the liver during the entire follow-up period (p=0,397). The amount of time between the end of SBRT and the appearance of such metastases had a significant effect on life expectancy: median for patients, new metastases in the liver appeared no later than 3 months after SBRT — 7 months, later — 31 months (p = 0.01333); similarly for 6 months: medians: 10 and 35 months (p = 0.04688).
The probability of occurrence of new metastases in the liver for 3 months was significantly associated with non-CRC histological types of the tumor (9.4% among patients with CRC and 28.6% among patients with non-CRC, p<0.04). The increase in the likelihood of new metastases in the liver within 6 months after SBRT was also significantly associated with the presence of tumor deposits outside the liver (primary tumor or distant metastases) at the time of the SBRT (20% in the group of patients, the spread of the tumor process at the time of treatment limited to the liver and 41.2% in the group of patients who at the time of the treatment had already detected extrahepatic deposits of the disease, p <0.05).
In CRC patients who had not performed such diagnostic studies as MRI and PET-CT during the month of the month when the SBRT started, the probability of detecting new liver metastases in the near future after SBRT was significantly higher. Thus, within 3 months after SBRT of metastasis of CRC in the liver, the risk of detecting new metastases in the liver was significantly lower among patients who were undergoing MRI (p = 0.017) or MRI / PET-CT (p = 0.04): 0% and 0% in comparison with 50% among patients who had only CT scan at the stage of the examination. Within 6 months after SBRT, the risk of detecting new metastases in the liver was also significantly lower among patients who were undergoing MRI (p = 0.01) or MRI / PET-CT (p = 0.012): 9% and 12% with 67% among patients who had only CT scan.
We found that the detection of new metastases in the liver for 6, and especially 3 months after SBRT, significantly decreases the life expectancy of patients. Significantly more often at these times of observation, new liver metastases were detected in those patients who had not performed an abdominal MRI with contrast for a month before SBRT. It should be assumed that in such patients the volume of the examination, including CT with contrast, did not allow to detect small metastases that became visible in the control examination after SBRT. So, the abdominal MRI with contrast is necessary before deciding to conduct a metastasis in the liver SBRT.