Association de radiothérapie et d’hormonothérapie dans la prise en charge des cancers localisés de la prostate : où en est-on ?

Les traitements combinés dans les formes à haut risque évolutif du cancer de la prostate (localisé ou non)

The high-risk group of prostate cancers is a heterogeneous group. A better definition of the criteria could bring a better selection of patients' selection in the combined local treatment or even in the general treatment. A treatment of these forms is the hormonoradiotherapy. The modalities of the radiotherapy and the hormonotherapy are to be defined and to be adapted according to prognostic factors of these patients. The surgery is also a possible treatment under certain conditions of selection of the patients and the adaptation of the surgical techniques. It can be combined either with other local treatments, radiotherapy for example, or even general ones. The pathological evaluation allows to identify overstaging and to avoid some unnecessary androgen therapy and also side effects. For the oligometastatic forms, the interest of the local treatment remains to appreciate. In the metastatic forms, a chemotherapy associated with the hormonotherapy must be proposed and seems to become a reference.

[Expected benefit of lymph node and seminal vesical dissection to decrease high-risk prostate cancer radiotherapy]

PURPOSE

In case of pelvic lymph node and seminal vesicle dissection followed by prostate cancer intensity-modulated radiotherapy, the objective of the study was to evaluate the dosimetric benefit of reducing the target volume.

PATIENTS AND METHODS

A total of 25 patients with high-risk prostate cancer had surgery first followed by intensity-modulated radiotherapy and androgen deprivation. Four treatment planning were simulated for each patient, based on two CT scans performed before and after surgery. The target volumes were: prostate-seminal vesicles-lymph nodes, prostate-lymph nodes, prostate-seminal vesicles and prostate only. The total dose was 46Gy in the seminal vesicles and lymph nodes, and 80Gy in the prostate.

RESULTS

Compared to prostate target volume only, the addition of seminal vesicles and lymph nodes multiplied by a factor of 1.6 and 6.5 the target volume, respectively. Decreasing the target volume from prostate-seminal vesicles-lymph nodes to prostate-seminal vesicles, to prostate only decreased the rectal wall mean dose from 49Gy to 42Gy, to 36Gy, and the risk of late rectal bleeding from 4.4% to 3.2%, to 2.4% (P<0.05), respectively. The bladder wall mean dose decreased from 51Gy to 40Gy, to 35Gy (P<0,05), respectively. Not irradiating the lymph nodes decreased the absolute risk of diarrhea by 11%.

CONCLUSION

Lymph node and seminal vesicle dissection before prostate cancer intensity-modulated radiotherapy allows decreasing moderately the risk of digestive toxicity.