Toxicity of Tomotherapy-Based Simultaneous Integrated Boost in Whole-Pelvis Radiation for Prostate Cancer

PURPOSE: The validity of tomotherapy-based simultaneous integrated boost (TOMOSIB) was assessed in terms of acute intestinal/urinary toxicity by comparing with 3-dimensional conformal radiotherapy (3DCRT) in cases of whole-pelvis radiation therapy (WPRT) for prostate cancer. MATERIALS AND METHODS: Thirty-eight consecutive patients who underwent curative WPRT were retrospectively reviewed. Twenty six (68.4%) received 3DCRT and the others (31.6%) were treated with TOMOSIB. A local boost to the prostate circumferential area was added to WPRT sequentially for 3DCRT and concomitantly for TOMOSIB. The total median prostate or prostatic bed dose was 64.8 Gy including median 45.0 Gy of WPRT. Acute toxicities were assessed according to RTOG criteria. RESULTS: Overall intestinal toxicity was lower in TOMOSIB group than 3DCRT group (p=0.008). When it was divided into rectum and non-rectum intestine (NRI), TOMOSIB showed borderline superiority only in NRI toxicity (p=0.047). For the urinary toxicity, there was no significant difference between two groups (p=0.796). On dosimetric analysis for the rectum and bladder, dose delivered to 80% (p<0.001) and volume receiving 25-40 Gy (p<0.001) were remarkably higher in 3DCRT. For the NRI, only maximum dose showed significant results between two groups (p<0.001). CONCLUSION: Intestinal toxicity should be verified with more detailed anatomic categorization such as rectum and NRI. TOMOSIB could not reduce urinary toxicity because of inevitably high dose exposure to the prostatic urethra. Current dosimetry system did not properly reflect intestinal/urinary toxicity, and suitable dosimetric guidelines are needed in TOMOSIB.

Toxicity of Tomotherapy-Based Simultaneous Integrated Boost in Whole-Pelvis Radiation for Prostate Cancer

PURPOSE: The validity of tomotherapy-based simultaneous integrated boost (TOMOSIB) was assessed in terms of acute intestinal/urinary toxicity by comparing with 3-dimensional conformal radiotherapy (3DCRT) in cases of whole-pelvis radiation therapy (WPRT) for prostate cancer. MATERIALS AND METHODS: Thirty-eight consecutive patients who underwent curative WPRT were retrospectively reviewed. Twenty six (68.4%) received 3DCRT and the others (31.6%) were treated with TOMOSIB. A local boost to the prostate circumferential area was added to WPRT sequentially for 3DCRT and concomitantly for TOMOSIB. The total median prostate or prostatic bed dose was 64.8 Gy including median 45.0 Gy of WPRT. Acute toxicities were assessed according to RTOG criteria. RESULTS: Overall intestinal toxicity was lower in TOMOSIB group than 3DCRT group (p=0.008). When it was divided into rectum and non-rectum intestine (NRI), TOMOSIB showed borderline superiority only in NRI toxicity (p=0.047). For the urinary toxicity, there was no significant difference between two groups (p=0.796). On dosimetric analysis for the rectum and bladder, dose delivered to 80% (p<0.001) and volume receiving 25-40 Gy (p<0.001) were remarkably higher in 3DCRT. For the NRI, only maximum dose showed significant results between two groups (p<0.001). CONCLUSION: Intestinal toxicity should be verified with more detailed anatomic categorization such as rectum and NRI. TOMOSIB could not reduce urinary toxicity because of inevitably high dose exposure to the prostatic urethra. Current dosimetry system did not properly reflect intestinal/urinary toxicity, and suitable dosimetric guidelines are needed in TOMOSIB.

Melatonin prevents inflammation and oxidative stress caused by abdominopelvic and total body irradiation of rat small intestine

We investigated the day-night differences in intestinal oxidative-injury and the inflammatory response following total body (TB) or abdominopelvic (AP) irradiation, and the influence of melatonin administration on tissue injury induced by radiation. Rats (male Wistar, weighing 220-280 g) in the irradiated groups were exposed to a dose of 8 Gy to the TB or AP region in the morning (resting period - 1 h after light onset) or evening (activity span - 13 h after light onset). Vehicle or melatonin was administered immediately before, immediately after and 24 h after irradiation (10, 2.0 and 10 mg/kg, ip, respectively) to the irradiated rats. AP (P < 0.05) and TB (P < 0.05) irradiation applied in the morning caused a significant increase in thiobarbituric acid reactive substance (TBARS) levels. Melatonin treatment in the morning (P < 0.05) or evening (P < 0.05) decreased TBARS levels after TB irradiation. After AP irradiation, melatonin treatment only in the morning caused a significant decrease in TBARS levels (P < 0.05). Although we have confirmed the development of inflammation after radiotherapy by histological findings, neither AP nor TB irradiation caused any marked changes in myeloperoxidase activity in the morning or evening. Our results indicate that oxidative damage is more prominent in rats receiving TB and AP irradiation in the morning and melatonin appears to have beneficial effects on oxidative damage irrespective of the time of administration. Increased neutrophil accumulation indicates that melatonin administration exerts a protective effect on AP irradiation-induced tissue oxidative injury, especially in the morning.

Efecto de la irradiación aguda sobre la morfometria del intestino delgado y la absorción de D-Xilosa en ratas / Effect of radiation on morphometry of small bowel and D-Xilose absorption in rats

En estudios previos en nuestro laboratorio, hemos demostrado el efecto de la radiación sobre la morfometría del intestino delgado de ratas, luego de 7 días de una única dosis abdominal externa de 10000 rad. Nuestra intención fue determinar el efecto del mismo esquema de radiación gamma, en ratas, sobre la morfometría del yeyuno y la absorción de D-Xilosa, 7, 14 y 21 días luego de la injuria, en comparación con un grupo control. La absorción de la pentosa fue medida a través de la xilosemia, 60 minutos luego de una dosis intragástrica (0,5 grs/kgr de pseo corporal) del azúcar. Resultados: En el grupo control (n: 22) el espesor de la mucosa fue de 880 ñ 40 micrones (X ñ DS), la altura vellositaria de 640 ñ 37.6 micrones y la xilosemia 15.91 ñ 11.39 mg%. Enel grupo irradiado a los 7 días (n: 11) el peso se redujo en 33.36 ñ 6.29% (vs. control p < 001), el espesor mucoso 666 ñ 97 micrones (p < 001), la altura vellositaria 466 ñ 66.9 micrones (p < 001), mientras que la xilosemia fue de 6.16 ñ 2.3 mg% (p < 05). Los valores a los 14 días (n:16) expresan una mejoría generalizada y una recuperación completa a los 21 días (n:14). En conclusión, las ratas irradiadas demostraron estar afectadas en su peso, morfometría y absorción de D-Xilosa, ésta alteración es máxima a los 7 días y se recupera completamente a los 21 días. En cambio, nosotros hemos hallado una absorción normal de D-Xilosa a los 21 días. Es de destacar que entre ese trabajo (3) y el presente existen diferencias metodológicas, lo que no los hace comparables. Hemos observado recientemente que, la correspondencia entre la absorción y las alteraciones morfométricas del yeyuno, se mantienen aún cuando se utiliza una sustancia radioprotectora como las prostaglandinas (8). Sin embargo esto no agrega luz a la discusión patogénica...