[ABSTRAK
Pendahuluan : Kemoradiasi pada kanker rektum menghasilkan radical oxygenspecies (ROS) yang dapat memicu kematian sel. ALDH1A1 merupakanantioksidan yang mampu mengurangi ROS dan merupakan marker sel puncakanker. Penelitian ini bertujuan untuk mengetahui hubungan kadar ALDH1A1dengan respon kemoradiasi berdasarkan metode RECIST 1.1 pada pasien kankerrektum stadium lanjut lokal.Metode : Penelitian ini merupakan studi retrospektif terhadap 14 pasien kankerrektum stadium lanjut lokal yang memenuhi kriteria inklusi dari januari 2012sampai januari 2015. ALDH1A1 diperiksa menggunakan metode ELISA darisampel blok parafin kanker rektum. Respon pengecilan tumor dari CT scan danMRI dihitung berdasarkan metode RECIST 1.1.Hasil : Didapatkan rerata kadar ALDH1A1 sebesar 9,014 ± 3,3 pg/mL, reratapersentase respon radiasi 7,89 ± 35,7 % dan diklasifikasikan berdasarkan RECISTdidapatkan proporsi respon parsial sebesar 28,6 % , respon stabil sebesar 50% danrespon progresif sebesar 21,4%. Terdapat korelasi negatif kuat yang bermakna(r = - 0,890 dan p < 0,001) antara kadar ALDH1A1 dengan respon kemoradiasiberdasarkan RECIST.Kesimpulan : pada penderita kanker rektum stadium lanjut lokal responkemoradiasi dipengaruhi oleh kadar ALDH1A1 dalam jaringan tumor. Semakintinggi kadar ALDH1A1 semakin buruk respon kemoradiasi.

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ABSTRACT
Introduction : Chemoradiation in rectal cancer produce radical oxygen species(ROS) wich can cause cell death. ALDH1A1 is an antioxidant that can reduceROS and known as cancer stem cell marker. The purpose of this study is todetermine the correlation between ALDH1A1 level with tumor shrinkage usingRECIST methode in locally advance rectal cancer.Methode : This is a retrospective study to 14 locally advance rectal cancerpatients who meet the inclusion criteria from january 2012 to january 2015.ALDH1A1 level was measured by ELISA from paraffin embeded tissue. Tumorshrinkage was measured from CTscan or MRI using RECIST 1.1 methode.Result : The mean ALDH1A1 level is 9,014 ± 3,3 pg/mL, the mean of tumorshrinkage is 7,89 ± 35,7 %, Partial respond proportion is 28,6 % , Stable disseaseproportion is 50% and progressive dissease proportion is 21,4%. There was asignificant strong negative correlation (r = -0,890, p < 0,001) betweenALDH1A1 with tumor shrinkage.Conclusion : This study showed that tumor shrinkage in locally advanced rectalcancer after chemoradiation is influenced by ALDH1A1 level. The increase odALDH1A1 level will decrease tumor shrinkage after chemoradiation;Introduction : Chemoradiation in rectal cancer produce radical oxygen species(ROS) wich can cause cell death. ALDH1A1 is an antioxidant that can reduceROS and known as cancer stem cell marker. The purpose of this study is todetermine the correlation between ALDH1A1 level with tumor shrinkage usingRECIST methode in locally advance rectal cancer.Methode : This is a retrospective study to 14 locally advance rectal cancerpatients who meet the inclusion criteria from january 2012 to january 2015.ALDH1A1 level was measured by ELISA from paraffin embeded tissue. Tumorshrinkage was measured from CTscan or MRI using RECIST 1.1 methode.Result : The mean ALDH1A1 level is 9,014 ± 3,3 pg/mL, the mean of tumorshrinkage is 7,89 ± 35,7 %, Partial respond proportion is 28,6 % , Stable disseaseproportion is 50% and progressive dissease proportion is 21,4%. There was asignificant strong negative correlation (r = -0,890, p < 0,001) betweenALDH1A1 with tumor shrinkage.Conclusion : This study showed that tumor shrinkage in locally advanced rectalcancer after chemoradiation is influenced by ALDH1A1 level. The increase odALDH1A1 level will decrease tumor shrinkage after chemoradiation, Introduction : Chemoradiation in rectal cancer produce radical oxygen species(ROS) wich can cause cell death. ALDH1A1 is an antioxidant that can reduceROS and known as cancer stem cell marker. The purpose of this study is todetermine the correlation between ALDH1A1 level with tumor shrinkage usingRECIST methode in locally advance rectal cancer.Methode : This is a retrospective study to 14 locally advance rectal cancerpatients who meet the inclusion criteria from january 2012 to january 2015.ALDH1A1 level was measured by ELISA from paraffin embeded tissue. Tumorshrinkage was measured from CTscan or MRI using RECIST 1.1 methode.Result : The mean ALDH1A1 level is 9,014 ± 3,3 pg/mL, the mean of tumorshrinkage is 7,89 ± 35,7 %, Partial respond proportion is 28,6 % , Stable disseaseproportion is 50% and progressive dissease proportion is 21,4%. There was asignificant strong negative correlation (r = -0,890, p < 0,001) betweenALDH1A1 with tumor shrinkage.Conclusion : This study showed that tumor shrinkage in locally advanced rectalcancer after chemoradiation is influenced by ALDH1A1 level. The increase odALDH1A1 level will decrease tumor shrinkage after chemoradiation]