RINECKER PROTON THERAPY CENTER STATUS REPORT: SIXTH MONTH OF CLINICAL OPERATION, SEPTEMBER ´09
PROTON IRRADIATION FOR PEDIATRIC CANCER
Proton radiation has to be preferred to X-rays when it comes to the treatment of cancer in children. International expert opinion (see reference) concur that proton radiation is preferred to X-rays with children and the young. Why is this the case? After all, exact “prospective randomized” comparative clinical trials with children do not exist – a fact, which will not change in the future. With children, radiation undergoes the same problem as pharmacotherapy: clinical trials in children are not permitted – and not only in Germany. Even less permitted are radiation tests on underaged persons since according to § 87 StrlSchV Abs. 1 the test person can give his consent only if he is contractually capable.
Hence, the preference for proton therapy in the case of pediatric cancers, often brain tumors that require irradiation, is justified solely by the computable superiority of the dose distribution of protons compared to X-rays (which is also generally applying to adults). The superior dose distribution in the body when using proton radiation often allows not only to increase the dose in the tumor but also decreases the exposure of the healthy tissue. Exactly this is the crucial advantage for the adolescent body.
Decrease of the irradiated volume with protons. Proton beams can be targeted in three dimensions; they stop in the tumor. Behind the tumor, i.e. the side that is averted from the radiation source, there is as opposed to X-rays no irradiation of the healthy tissue. The improvement can easily be quantified with the standard protocols for proton scanning (see Status Report April 09):
Exposure of infantile and adolescent tissue to radiation with nonlethal doses, thus collateral damages of the tumor treatment, leads with a frequency of up to 1% per subsequent year to radiation-induced secondary tumors caused by therapeutically intended radiation. These secondary tumors are mostly malign sarcomas. It is well known that this tumor triggering may represent a higher danger than the chance of a recurrence of the initial tumor especially with children who have a long life expectancy.
Decrease in the exposure of healthy tissue to radiation using protons. As repeatedly elucidated in our internet reports, the dose in front of the tumor, i.e. along the path of the radiation from the radiation source until the tumor, is not higher but lower than in the tumor when using the proton scanning method. This physical effect is significant, multiplies the reduction of the irradiated volume, and can once again be quantified on the basis of the standard protocols of the RPTC:
This decrease in dose with protons is especially effective if these are, as is the case in the RPTC, applied with the precise and free of scattered neutron radiation scanning method – not as it is the case in older facilities using the scattering-method (see Status Report June 09). The decrease in dose does not only lead to a reduction of the above discussed probability of the subsequent incidence of secondary tumors, but also has a positive effect on the tissue growth: adolescent tissue is particularly sensitive to radiation-induced cicatrization. For example, mammary glands of girls in their infancy, which are exposed to radiation, stop growing altogether after.
CASE STUDIES OF CHILDREN AND ADOLESCENTS IRRADIATED AT RPTC
Case Study rhabdomyosarcoma:
In September 2009 we began with the proton treatment of a seven-year-old girl who became ill with a widespread tumor in the upper neck area: a malign blastoma of the cervical muscles, a rhabdomyosarcoma. The tumor infiltrated from the right parotid gland to the nasopharynx up to the left opposite side so that a surgical procedure was not feasible. The tumor also continued to grow under chemotherapy. Primarily because of the limitation of the radiation dose to the infiltrated tissue and the best possible sparing of the healthy tissue in comparison to X-ray therapy the attending child-oncologists and the parents chose proton therapy. The girl tolerates the proton therapy very well. The obstructed nasal respiration has improved as a result of the tumor reduction, difficulty in swallowing did not occur. In addition, because of the noticeable sparing of the left parotid gland (figure) the treatment did not lead to a dry mouth. The mother has reported that the girl has already become stronger and more active in the course of the therapy.
Case study optic nerve glioma WHO I:
At the same time we began with the treatment of a seven-year-old girl suffering from a large (4.2 x 3.8 x 4.5 cm) tumor inside the cranial cavity which invades the optic nerve at the chiasm and has already caused blindness on the affected side. After several chemotherapies in the past have been unsuccessful in reducing the optic nerve glioma and the growth of this space-occupying lesion has even made a shunt-operation, i.e. shunting of the cerebrospinal fluid into the abdomen necessary, irradiation with protons was indicated. Because of the location of the tumor in the area of the optic chiasm (crossing of optic nerves) and the hypothalamus (in the brainstem) the danger of damaging the surrounding structures is naturally very high. Particularly in such cases the benefits of an exact and gentle scanning-proton-irradiation show to advantage. The precision of the positioning using vacuum contour beds, fixing of the upper jaw in a maxillary mold and the performance of the therapy in a sleep like state (deep sedation) are further measures to guarantee the optimal therapy progress. The young patient tolerated the 10 (out of 27) so far administered irradiations (figure) very well. There was no incidence of side-effects or complications.
Case study Ewing sarcoma:
A 16-year-old patient who was suffering from an Ewing sarcoma of the thoracic spine was irradiated with protons at our center. Several adjoining thoracic vertebral bodies were forming the target area. The maximum dose tolerated by the spinal cord has not been exceeded unlike the comparative dose calculation for X-rays. The patient received 30 treatments (figure). Undesirable aftermath of radiation occurred in the category of acute side effects (side effects during and up to three months after completion of the radiation) in the form of a routinely spontaneously healing radiation erythema (radiation induced skin redness). The post treatment observation time does not yet suffice for an assessment of eventual late side effects or the chances of recovery. A chemotherapy was applied in an external clinic in the run-up and parallel to the proton therapy.
COOPERATION FOR PROTON THERAPY FOR CHILDREN FROM ISRAEL
Israel has a pediatric hospital which is exceptionally large on an international scale and dedicated exclusively to the treatment of children: The Schneider`s Children Hospital. A delegation of physicians from this children`s hospital which is affiliated to Tel Aviv University visited the RPTC in Munich on 07.09.2009. Amongst them was the head of the radio-oncological division and the head of the oncologic division – both specialized in the treatment of children. The visit served the preparation of a cooperation for the proton irradiation of children. Visits of experts of a further Israeli university are planned as well.
A cooperation with Israeli universities is highly satisfactory for the RPTC since there exists an admirable engagement for specialized child treatment (pediatrics) in Israel, the Israeli medicine is highly progressive and advanced and because the colleagues, much to their regret, don’t have a proton therapy possibility in their country yet. However, in Israel there is all the expertise at hand which is needed to pre-select for us the children that are suitable for proton therapy and to conduct any follow-up-treatments on the highest scientific level.
The RPTC will also conduct these treatments for Jewish and Arabic children from Israel within the framework of a charity-engagement.