Radiotherapy of prostate cancer

Radiotherapy of prostate cancer

The percutaneous radiotherapy (external radiation) and brachytherapy (internal radiation) can in localized and locally advanced prostate cancer without distant metastases are used, the former also with lymph node involvement.

Radiation therapy has, the tumor cells by radiation to damage to the target so that they die, while sparing the surrounding healthy tissue as much as possible. For this, different types of radiation coming from different sources in question (eg, high-energy photon radiation such as ultra-hard X-rays and gamma rays , particle beams). The case transferred to the target area of energy you are as absorbed dose in Gray at (abbreviated Gy = joules per kilogram).

In most cases the target volume from the findings and a CT (to be computed tomography ) or MRI ( magnetic resonance imaging ) created a three-dimensional computer model. This can then be the distribution of the radiation plan that everywhere the minimum dose is reached (in prostate cancer 70-72Gy) and the burden of radiation-sensitive organs such as bladder and bowel below a certain threshold dose remains.

A distinction is curative (aimed at healing) of a palliative radiation therapy, which is used for the relief of tumor-related symptoms (eg, by irradiation of bone metastases, see palliative care in prostate cancer ). The curative form applies in prostate cancer in many cases as an alternative to surgery (RPE, see radical prostatectomy ), especially in patients who are potential complications of radiation therapy (see below) accept and reject those of the RPE, in patients who can not have surgery , as well as in older patients. Be used for this percutaneous radiotherapy and brachytherapy:

Technique of percutaneous radiotherapy

The external radiation (external) through the skin (percutaneous) is also called external beam radiation therapy and now is usually done on an outpatient basis without anesthesia using a linear accelerator. You will be based on a so-called three-dimensional conformal planning, in less late complications (see below) occur. This technique also allows for a dose increase, which improves the results, but it is associated with a greater risk of complications.

The target volume is irradiated on 4-7 fields from different directions, which are hidden individually enforcement agencies and not covered by any field. Location and dose of irradiation is continuously measured and corrected if necessary. In order to damage the tumor stronger and to protect healthy tissue more, the total dose is also divided into several single doses (fractionated). Usual ever 1.8-2.0 Gy, five days per week, 70Gy are thus in 7-8 weeks.

A further development is the intensity-modulated radiotherapy (IMRT german, intensity modulated radiotherapy). It allows a higher single dose, resulting in the shortening of the duration of treatment (eg 70Gy by 28 doses, each of 2.5 Gy in just over five weeks) or can be used to increase the total dose. The latest IMRT technique called VMAT (English volumetric modulated therapy ARC) and provides an uninterrupted change of direction.

Technique of brachytherapy

This is a "short segment" radiation therapy (brachy = short), in which a radionuclide (radioactive chemical element) is introduced directly into the prostate. Since it is in the interstitial tissue (interstitium) of the organ, called brachytherapy and interstitial radiotherapy.The insertion is usually done during an outpatient or short hospital stay in "spinal anesthesia", by hollow pins to the dam of (perineal) under TRUS control (see transrectal ultrasound are advanced) in the prostate. Location and dose of radiation can be scheduled thereby be directly measured and corrected. We distinguish the following two forms:

LDR brachytherapy (. engl of low-dose rate = low dose rate, also reduced low-dose brachytherapy): This small pins (English seeds) permanently implanted into the prostate. They give off their radiation over a long period of time and included as a radiation source of iodine-125 (145Gy) or palladium-103 (125Gy). A subsequent percutaneous radiotherapy to increase the dose is possible. A not too large prostate (max. 60ml) and low urinary symptoms (considered to be favorable IPSS to 8). After a TURP (surgery for prostate enlargement, see also surgical procedure for BPH treatment ) to LDR brachytherapy be more difficult, and there is a higher risk for subsequent urinary incontinence (see complications).

HDR brachytherapy (. engl of high-dose rate = high dose rate, also reduced high-dose rate brachytherapy): For this one uses the much more intense radiant Iridium 192nd It is automatically inserted during the procedure via the needles into the prostate and after a few minutes (so-called afterloading technique). Two common procedures, followed by external beam radiotherapy. This method is used to increase the dose.

Lymphadenectomy

For the decision to radiotherapy the risk plays a role for lymph node involvement. It increases with the local extent of the tumor and can be estimated on the basis of the findings, for example, using the Partin tables (see stages and prognosis ). Depending on the result may come into question a lymphadenectomy (surgical removal of lymph nodes). This is also endoscopically ("keyhole surgery") and in sentinel technique possible (selectively removing Wächterlymphyknoten, more on the topic in the section "radical prostatectomy" underlymphadenectomy ).

Radiotherapy for localized prostate cancer

Percutaneous radiotherapy: It is an opportunity for primary treatment of clinically (ie determined by tests) localized prostate cancer (cT1-2 N0 M0, the TNM system s growth and spread ). The following recommendations are based on a classification of the risk of progression of the tumor in low, medium and high, which is made ​​on the basis of findings (seetreatment planning ).
Patients with a tumor with a low risk to be irradiated percutaneously with at least 70-72Gy. They have no survival benefit of neoadjuvant (before starting) or adjuvant (later onset) hormone therapy . Patients with a tumor with moderate risk, however, should receive a higher radiation dose and / or an additional hormone therapy. For them, a neoadjuvant and / or adjuvant hormonal therapy are applied which should be at most as short-term therapy (concomitant 3 months before the start of radiation plus 3 months). In patients with a tumor with a high risk in addition to irradiation, neoadjuvant or adjuvant hormone therapy for at least two, better three years is to be performed, which prolongs survival, a radiation dose of more than 70-72Gy with hormone therapy prolongs survival without re-increase of PSA - value.

LDR brachytherapy: As sole therapy is an option for primary treatment of clinically localized prostate cancer with low risk (see at-risk groups treatment planning ). In patients with a tumor with a medium risk is some evidence for the combination with external beam radiotherapy, but there is no recommendation. Patients with a tumor at high risk should receive no single LDR brachytherapy, the combination with external beam radiotherapy and / or hormone therapy should be performed only in the context of studies.

HDR brachytherapy: It is a way of primary treatment of clinically localized prostate cancer with intermediate and high risk combined with external beam radiotherapy. The effect of additional hormone therapy is still unclear. A sole HDR brachytherapy for tumors with low risk should be performed only in the context of studies.

Radiotherapy of locally advanced prostate cancer

Percutaneous radiotherapy: It is in combination with hormone therapy an option for primary treatment of clinically (ie by means of studies identified) locally advanced prostate cancer (cT3-4 N0 M0, the TNM system s growth and spread ). This combination is superior to both a sole external beam radiotherapy, as well as a sole hormonal therapy. Patients with such a tumor in which a local (local) treatment is planned, to be informed about the pros and cons of both of these combination therapy and radical prostatectomy with lymphadenectomy (lymph node removal, see below).
Patients with locally advanced prostate cancer to be irradiated percutaneously with at least 70-72Gy. If they opt for percutaneous radiotherapy, they are expected to receive hormone therapy, namely adjuvant (starting later) or neoadjuvant (before starting) and adjuvant.Neoadjuvant hormonal therapy is to take place for 2-3 months, adjuvant for at least 2 years, and the total duration is at least 2, better be 3 years. The effect of additional irradiation of the lymphatic drainage in the basin is still unclear.

HDR brachytherapy: It is used in combination with external beam radiotherapy an option for the treatment of locally advanced prostate cancer category cT3 (clinically, ie, determined by means of tests: cT3 N0 M0, the TNM system s growth and spread ). In a cT4 tumor HDR brachytherapy is not displayed. The effect of additional hormone therapy is not yet clear.

Radiotherapy for lymph node involvement

In a histological (histological) secured lymph node involvement (pN1) stand for the local treatment, radical prostatectomy ( RPE ) and radiation therapy available for the systemic (general) treatment, the hormone therapy. A reliable comparison of the methods, either alone or in combination, is not possible due to the current data situation. The decision must be made ​​on an individual. A percutaneous radiotherapy used in such a case, it is to be used in combination with at least 2, preferably 3 years of hormone therapy. Whether the irradiation of the lymphatics (lymph nodes or the distance so) in cases of proven lymph node involvement has a positive effect is still unclear. An already clinically detectable lymph node involvement (cN1) proves on histological examination usually as pronounced, suggesting a hormonal therapy.

Complications of radiotherapy

The damage to the tissue with radiation can lead to complications, the frequency decreases as the radical prostatectomy (RPE) with the experience of the physician and improved techniques.On the other hand, there are no preventive treatment with medication. Acute complications (within three months) are rare. An exception is the LDR brachytherapy, after many patients temporarily (more) have problems with urination due to the engagement of the prostate. This is likely for HDR brachytherapy (insufficient data) apply.

Late complications are more frequent and possible even after many years because of the delayed effect of radiation, eg bladder inflammation ( cystitis ), blood admixture to the urine (hematuria ), urinary incontinence (mainly urge incontinence caused by irritation of the bladder, see urinary incontinence ), cicatricial narrowing (stricture) of the urethra, proctitis (inflammation of the rectum), tenesmus, diarrhea, blood admixture to the chair, edema of the legs (fluid retention by obliteration of the lymphatic vessels), chronic pelvic pain syndrome (by migration of the seeds after LDR

brachytherapy). Again, there are few data to HDR brachytherapy. Other major late complications are:
Erectile Dysfunction: The disorder of erection (stiffening member) affects approximately equal numbers of patients one year after percutaneous radiotherapy after LDR brachytherapy without additional irradiation and after radical prostatectomy with nerve sparing. Cause, besides the injury to the erectile nerves and the psyche (eg, a depressed mood). The touch sensitivity of the skin (eg on the penis), the libido ("Lust") and the ability to orgasm are not affected by the rays. There are numerous methods for the treatment (see rehabilitation anderectile dysfunction ).

Secondary tumors: Radiation dose to the surrounding healthy tissue increases the risk of something there to develop a second malignant tumor, especially for rectal cancer (cancer of the rectum) and bladder cancer. This is true for percutaneous radiotherapy and LDR brachytherapy, HDR brachytherapy for the corresponding long-term data are still lacking.

Relapse therapy

In contrast to radical prostatectomy (RPE) of the PSA level decreases after successful radiotherapy only very slowly to a low point (nadir) from, after percutaneous radiotherapy on average over 18-36 months, after LDR brachytherapy also over a considerably longer period of time. However, it comes up relatively often to a "PSA bounce" (English for high jumping), an increase with fluctuating values.
This makes it difficult to recognize a so-called biochemical recurrence (BCR, laboratory signs of a recurrence of the disease). After radiotherapy alone one assumes such, if the PSA level increases by more than 2ng/ml on the Nadir (not zero, therefore also called PSA progression), which must be confirmed by at least one additional measurement (Phoenix definition ). It may be caused by a recurrence of the tumor at the original site (tumor recurrence, "local recurrence") or the growth of metastases (secondary tumors) to lymph nodes or other parts of the body ("systemic relapse").

If it is pulled in a patient with a biochemical recurrence after radiation therapy a local treatment (see below) into account, one should try a local recurrence with transrectal prostate biopsy to secure. In addition, a distinction between a local and a systemic recurrence should be sought on the basis of PSA doubling time (PSA-DT), the time between radiotherapy and increase in PSA and the Gleason score . The shorter the PSA DT (for example, less than 3 months) and the distance to the treatment and the higher the Gleason score (greater than 7), the more likely it is a systemic recurrence, wherein a hormone is eligible. However, the latter is the biochemical recurrence no standard therapy.

For they considered to be local recurrence has the following recommendations: In patients with favorable criteria (eg elderly patients, PSA-DT more than 10 months, later rising PSA, Gleason score less than 8, no infection of the seminal vesicles or lymph nodes) is the Wait an option (see active monitoring ). If the PSA progression is not very likely to return metastases, the so-called salvage prostatectomy (SRP, "rescue" RPE) is a treatment option. Conveniently for this are, for example, a tumor with a low risk of having a PSA rise after more than 3 years and a PSA-DT of more than 12 months. However, the results with respect to the SRP erectile dysfunction, and urinary incontinence are significantly worse than for a RPE without radiotherapy. Before the SRP, the local recurrence should be confirmed by biopsy (see above).The SRP should be done as early as possible is because of the radiation-induced changes of the tissue to perform (especially after HDR brachytherapy) by an experienced surgeon.