Clinical diagnosis
Case 325
【Progress】
She received radiation treatment with heavy carbon particles of 60Gy/4fr. She received EOB MRI for investigating recurrence and metastases which showed gradual tumor decrease three months later (Fig.3) and marked tumor shrinkage (Fig. 4).
【Discussion】
Hepatocellular carcinoma (HCC) is relatively radio-sensitive, more susceptible to radiation doses rather than metastatic tumor and cholangiocellular carcinoma. Radiation doses of 40 to 45 Gy are enough to control HCC potency, while doses of 60Gy are not sufficient to control metastatic tumor from digestive organs (1-3).
Meanwhile, tolerant doses of liver parenchyma are around 40Gy. Cirrhotic liver which is usually associated with HCC is thought to be lower than non-cirrhotic liver, less than 30 Gy. Further, liver is surrounded by organs sensitive to radiation doses. Small intestine or duodenum is susceptible to radiation: tolerant doses, 40 Gy. Tolerant doses of spinal cord are < 50 Gy and those of kidney are < 30 Gy (1, 3).
Then, because not just that liver is itself radio-sensitive organ, but also that liver is surrounded by radio-sensitive organs, conventional radiation treatment using two port irradiation or multiport irradiation is hesitated to be supplied.
There are two types of radiation treatments for HCC beyond disadvantages of radio-circumstance on liver and its surroundings. One type is the method using Bragg peak. Proton beam and carbon beam own Bragg peak that imply radiation dose peak is formed at a certain distance from surface which indicates that from a viewpoint of physics, particles decay at a certain distance with its energy release causes cell destruction. Widening of Bragg peak is formed by modifying energy of particles can apply tumor sizes. It makes possible to create irradiation planning corresponded to tumor size with prescribing enough doses to control tumor and with less tolerant doses to liver parenchyma and its surrounding radio-sensitive organ. Another type is functional-liver-reserved three dimensional conformal radiotherapy(3-DCRT) using Tc-99m-GSA (galactosyl human serum albumin) that accumulate to functional liver (3-5). Radiation treatment planning is created to utilize non-functional liver: radiation beams to irradiate tumor mass through non-functional liver to decrease liver damages as least as possible. Further, radiation beams are planned to irradiate the surrounding radiosensitive organs whose doses do not exceed tolerant doses of each organ (3-5). Combination of functional-liver-reserved 3-DVRT and transcatheter arterial chemoembolization can bring the longer survival for HCC patients with portal tumor thrombus even if not always radical treatments (4-7).
In our case, she made a choice of carbon beam radiotherapy of 60 Gy/4 fractions for HCC, inducing shrinkage of the tumor with preserve functional liver T1WIMRI depicted, expecting complete response and long survival.
【Summary】
We presented an eighty-six-year-old female with HCC of 66mm which was treated by carbon beam radiotherapy, inducing marked shrinkage six months later depicted on MRI. It is borne in mind that radiation therapy for HCC faces various negative factors: low tolerant doses of liver cirrhosis and its surrounding radiosensitive organs of duodenum, kidney and spinal cord. To avoid radiosensitive organs and to concentrate radiation beams to HCC target, proton beam or carbon particles using Bragg peak and functional-liver-reserved 3DCRT using Tc-99m-GSA are used.
【References】
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2024.2.22