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Hypoxia, p53-expression and survival in cervical cancers
Proceedings
202
Hypoxia, p53-expression
G. Haensgen.’
U. Krause,’
‘Dept. of Radiotherapy, Halle, H&e, Germany
and survival
S. Pigorsch,i
of the 42nd Annual ASTRO Meeting
213
in cervical cancers
F. W. Rath’ J. Dunst’
Martin-Luther-Uni~,e~sit~
Ha&,
Halle, Germany ‘Dept. of Pathology, Martin-Luther-
University
Background: Recent experimental investigations have demonstrated that hypoxia leads to increased genomic instability and exerts a selection pressure favoring the survival of cells with decreased apoptotic potential. Most cervical cancers in Europe correlate with infection of human papillomavirus HPV16 which results in a functional loss of p53 and impairment of apoptosis. The degradaded p53 can be detected immunohistologically due to its increased half-life. If all these hypothesis are correct, one should expect differences in hypoxic versus non-hypoxic cervical cancers with regard to p53-positivity. We have investigated the impact of ~53 and hypoxia on survival in patients with advanced cervical cancers. I Material and Methods: From 1995 through 1999, 70 patients with locally advanced squamous cell cervical cancer (FIG0 II-IVA) who underwent definitive radiotherapy with curative intent underwent pretreatment oxygenation measurement by p02-histogrpahy using the Eppendorf probe. Tumors were considered as being hypoxic if they contained p02-values <5mmHg. The p53-status was analyzed in pretreatment biopsies by immunohistology using the D07-antibody. Because of the short half-life of wildtyp-p53, immunhistologically p53-negativ-tumors (p53-) are considered as having wtp53 whereas tumors with positive immunohistolocal staining (p53+, positive staining in ~10% of tumor cells) have probably mutated or inactivated ~53. The DNA index was determined by flow cytometry. The statistical analysis was performed using statistical package SPSS. Results: Stage and anemia were independent of prognostic factors with 3.year cause-specific survival rates of 65% for stage IIb (n = 14). 63% for stage IIIb (n = 49) and 29% for stage IVa (n = 7) 29%. Patients with a hemoglobin <1 lg/dl (n = 14) had a lower survival than patients with a Hb >I Ig/dl. 27% versus 65%, p = 0.003. The p02-measurments revealed no hypoxia in 21/70 and hypoxia in 49 tumors. Patients with non-hypoxic tumors had a 3.year-survival of 70% as compared to 48% for hypoxic tumors, p = 0.072.60/70 biopsies were p53+ and 10 were negative with 3-year-survival figures of 79% versus48%, p = 0. I 1 The mean p53-expression in cancers without hypoxia was 12.7% as compared to 27.1% in hypoxic tumors, p = 0.012. In a Cox-regression model (adjusted to stage and pretreatment hemoglobin) the best survival figures were obtained in patients with p53-negative tumors (only l/10 was hypoxic), followed by patients with p53-positive but non-hypoxic tumors. Patients with both hypoxic and p53-positive tumors had the worst survival. The DNA index in 60 p53-positive tumors differed with regard to the presence of hypoxia: hypoxic cancers had a (non-signiticant) higher DNA-index as non-hypoxic tumors, 2.2 2 3.1 versus 12 i- 0.3. p53-negative tumors had identical DNA-indices irrespective of the presence of hypoxia. Conclusions: High stage and anemia are classical prognostic factors in cervical cancers. In our study. immunohistological p53-status and the presence of hypoxia were weak prognostic factors. However. the combination of both parameters was associated with a significant decrease in survival. This finding together with the difference in the DNA-index in hypoxic p53-positive tumors supports the hypothesis that hypoxia promotes malignant progression.
203 car b on T. Nakano.
b earn therapy overcame
radiation
resistant nature originated
from hypoxia for cervical cancer
Y. Suzuki, T. Ohono, S. Morita H. Tsujii
National Institute of Radiological
Sciences, Japan, Chiba-shi, Japan
Purpose: The existence of hypoxic cells is well recognized as one of the major factors of resistance against radiation therapy and local failure. The high LET particles are believed to decrease radiation resistance of tumors originated from hypoxia and different radiation sensitivity in cell cycle. However, no proof of the effect have been provided by clinical trials and related clinical researches. Hence, we investigated the relationship between intratumoral pO2 before and during radiation therapy and local control in patients with cervical cancer treated with photon and carbon beams to assess radiation biological aspect of the high LET carbon beam therapy on cervical cancer. Materials and Methods: This study involved 23 patients with stage 3B bulky and 4A squamous cell carcinomas of the cervix treated with high LET carbon beams and, as control, 30 patients with stage 2B to 4A disease treated with conventional photon beams between 1995 and 1998. The mean age of the patients was 618 0 } 113 years. Measurement of intratumoral pO2 was made by using a needle-type polarographic oxygen electrode (POE-ION, Intermedical, Tokyo, Japan) and p02-monitoring machine (PIOO, Intermedical). The electrode was inserted into 1 cm beneath surface of tumor before treatment and at 1 week after the tirst irradiation. Results: The mean intratumoral pO2 of patients treated with photon and carbon beams before treatment were 15.4 0 } 9.3 mm Hg and 16.5 0 ) 9.0 mm Hg, respectively. At 1 week after the first irradiation, the mean intratumoral pO2 of patients treated with photon and carbon beams were 24.6 0 ) 117 mm Hg and 24.4 0 ) 9.7 mm Hg, respectively. There was a significant increase in the pO2 at 1 week after the first irradiation with compared to the pO2 before treatment in both treatment. In patients treated with photon beams, the 3-year local control rate of intratumoral pO2 equal or less than 20 mm Hg before treatment was 54% and it was significantly lower than the 100% of intratumoral pO2 over 20 mm Hg (p = 0.035). The 3-year local control rate of intratumoral pO2 equal or less than 20 mm Hg at 1 week after the first irradiation was 26% and it was significantly lower than the 94% of intratumoral pO2 over 20 mm Hg (p = 0.006). However, in patients treated with carbon beams, there were no significant difference in the 3-year local control rate between intratumoral pO2 equal or less than 20 mm Hg and over 20 mm Hg both before treatment (64% vs. 678, p = 0.87) and at 1 week after the first irradiation (50% vs. 73%, p = 0.29). Conclusion: The present study indicated the reoxygenation phenomenon occurred within 1 week after initiation of carbon beam therapy, similar to photon beam therapy. The similar survival and local control rates between the oxygenated and hypoxic tumors before treatment indicated that tumor oxygenation status was less important for local control in carbon beam therapy. This study is the first clinical confirmation that high LET beam irradiation may reduce radiation resistance of hypoxic tumors.
202
Hypoxia, p53-expression
G. Haensgen.’
U. Krause,’
‘Dept. of Radiotherapy, Halle, H&e, Germany
and survival
S. Pigorsch,i
of the 42nd Annual ASTRO Meeting
213
in cervical cancers
F. W. Rath’ J. Dunst’
Martin-Luther-Uni~,e~sit~
Ha&,
Halle, Germany ‘Dept. of Pathology, Martin-Luther-
University
Background: Recent experimental investigations have demonstrated that hypoxia leads to increased genomic instability and exerts a selection pressure favoring the survival of cells with decreased apoptotic potential. Most cervical cancers in Europe correlate with infection of human papillomavirus HPV16 which results in a functional loss of p53 and impairment of apoptosis. The degradaded p53 can be detected immunohistologically due to its increased half-life. If all these hypothesis are correct, one should expect differences in hypoxic versus non-hypoxic cervical cancers with regard to p53-positivity. We have investigated the impact of ~53 and hypoxia on survival in patients with advanced cervical cancers. I Material and Methods: From 1995 through 1999, 70 patients with locally advanced squamous cell cervical cancer (FIG0 II-IVA) who underwent definitive radiotherapy with curative intent underwent pretreatment oxygenation measurement by p02-histogrpahy using the Eppendorf probe. Tumors were considered as being hypoxic if they contained p02-values <5mmHg. The p53-status was analyzed in pretreatment biopsies by immunohistology using the D07-antibody. Because of the short half-life of wildtyp-p53, immunhistologically p53-negativ-tumors (p53-) are considered as having wtp53 whereas tumors with positive immunohistolocal staining (p53+, positive staining in ~10% of tumor cells) have probably mutated or inactivated ~53. The DNA index was determined by flow cytometry. The statistical analysis was performed using statistical package SPSS. Results: Stage and anemia were independent of prognostic factors with 3.year cause-specific survival rates of 65% for stage IIb (n = 14). 63% for stage IIIb (n = 49) and 29% for stage IVa (n = 7) 29%. Patients with a hemoglobin <1 lg/dl (n = 14) had a lower survival than patients with a Hb >I Ig/dl. 27% versus 65%, p = 0.003. The p02-measurments revealed no hypoxia in 21/70 and hypoxia in 49 tumors. Patients with non-hypoxic tumors had a 3.year-survival of 70% as compared to 48% for hypoxic tumors, p = 0.072.60/70 biopsies were p53+ and 10 were negative with 3-year-survival figures of 79% versus48%, p = 0. I 1 The mean p53-expression in cancers without hypoxia was 12.7% as compared to 27.1% in hypoxic tumors, p = 0.012. In a Cox-regression model (adjusted to stage and pretreatment hemoglobin) the best survival figures were obtained in patients with p53-negative tumors (only l/10 was hypoxic), followed by patients with p53-positive but non-hypoxic tumors. Patients with both hypoxic and p53-positive tumors had the worst survival. The DNA index in 60 p53-positive tumors differed with regard to the presence of hypoxia: hypoxic cancers had a (non-signiticant) higher DNA-index as non-hypoxic tumors, 2.2 2 3.1 versus 12 i- 0.3. p53-negative tumors had identical DNA-indices irrespective of the presence of hypoxia. Conclusions: High stage and anemia are classical prognostic factors in cervical cancers. In our study. immunohistological p53-status and the presence of hypoxia were weak prognostic factors. However. the combination of both parameters was associated with a significant decrease in survival. This finding together with the difference in the DNA-index in hypoxic p53-positive tumors supports the hypothesis that hypoxia promotes malignant progression.
203 car b on T. Nakano.
b earn therapy overcame
radiation
resistant nature originated
from hypoxia for cervical cancer
Y. Suzuki, T. Ohono, S. Morita H. Tsujii
National Institute of Radiological
Sciences, Japan, Chiba-shi, Japan
Purpose: The existence of hypoxic cells is well recognized as one of the major factors of resistance against radiation therapy and local failure. The high LET particles are believed to decrease radiation resistance of tumors originated from hypoxia and different radiation sensitivity in cell cycle. However, no proof of the effect have been provided by clinical trials and related clinical researches. Hence, we investigated the relationship between intratumoral pO2 before and during radiation therapy and local control in patients with cervical cancer treated with photon and carbon beams to assess radiation biological aspect of the high LET carbon beam therapy on cervical cancer. Materials and Methods: This study involved 23 patients with stage 3B bulky and 4A squamous cell carcinomas of the cervix treated with high LET carbon beams and, as control, 30 patients with stage 2B to 4A disease treated with conventional photon beams between 1995 and 1998. The mean age of the patients was 618 0 } 113 years. Measurement of intratumoral pO2 was made by using a needle-type polarographic oxygen electrode (POE-ION, Intermedical, Tokyo, Japan) and p02-monitoring machine (PIOO, Intermedical). The electrode was inserted into 1 cm beneath surface of tumor before treatment and at 1 week after the tirst irradiation. Results: The mean intratumoral pO2 of patients treated with photon and carbon beams before treatment were 15.4 0 } 9.3 mm Hg and 16.5 0 ) 9.0 mm Hg, respectively. At 1 week after the first irradiation, the mean intratumoral pO2 of patients treated with photon and carbon beams were 24.6 0 ) 117 mm Hg and 24.4 0 ) 9.7 mm Hg, respectively. There was a significant increase in the pO2 at 1 week after the first irradiation with compared to the pO2 before treatment in both treatment. In patients treated with photon beams, the 3-year local control rate of intratumoral pO2 equal or less than 20 mm Hg before treatment was 54% and it was significantly lower than the 100% of intratumoral pO2 over 20 mm Hg (p = 0.035). The 3-year local control rate of intratumoral pO2 equal or less than 20 mm Hg at 1 week after the first irradiation was 26% and it was significantly lower than the 94% of intratumoral pO2 over 20 mm Hg (p = 0.006). However, in patients treated with carbon beams, there were no significant difference in the 3-year local control rate between intratumoral pO2 equal or less than 20 mm Hg and over 20 mm Hg both before treatment (64% vs. 678, p = 0.87) and at 1 week after the first irradiation (50% vs. 73%, p = 0.29). Conclusion: The present study indicated the reoxygenation phenomenon occurred within 1 week after initiation of carbon beam therapy, similar to photon beam therapy. The similar survival and local control rates between the oxygenated and hypoxic tumors before treatment indicated that tumor oxygenation status was less important for local control in carbon beam therapy. This study is the first clinical confirmation that high LET beam irradiation may reduce radiation resistance of hypoxic tumors.