Tesis

Perbandingan Respons Tumor dan Dosimetri Brakiterapi Intrakaviter Tanpa Interstisial dan dengan Interstisial Terhadap Pasien Kanker Serviks Stadium Lokal Lanjut Pasca Konkuren Kemoradiasi dengan Residual Tumor.

Pendahuluan: Kanker serviks stadium lokal lanjut adalah salah satu masalah kesehatan utama di Indonesia. Brakiterapi intrakaviter (ICBT) merupakan standar radioterapi adjuvan pasca radiasi eksterna. Namun, pada kasus dengan residu tumor, bentuk asimetri, atau keterlibatan parametrium, cakupan dosis dengan ICBT saja sering tidak memadai. Kombinasi brakiterapi intrakaviter-interstisial (IC+ISBT) dikembangkan untuk meningkatkan cakupan dosis terhadap high-risk clinical target volume (HR-CTV). Data lokal yang membandingkan kedua teknik ini masih terbatas. Metode: Penelitian observasional retrospektif dilakukan terhadap 98 pasien kanker serviks stadium lokal lanjut pasca kemoradiasi di RSUPN Dr. Cipto Mangunkusumo. Subjek dibagi menjadi kelompok ICBT (n=62) dan IC+ISBT (n=36). Variabel yang dianalisis meliputi respons tumor (complete Respons / CR vs non-CR), D90 HR-CTV, D2cc organ at risk (bladder, rektum, sigmoid), dosis titik A1 dan A2, toksisitas akut, serta overall treatment time (OTT) brakiterapi. Analisis bivariat dilakukan menggunakan Chi-square/Fisher Exact dan uji MannWhitney. Post hoc power dihitung berdasarkan nilai Chi-square. Hasil: kelompok IC+ISBT menunjukkan angka CR lebih tinggi dibandingkan ICBT (80.6% vs 54.8%, p = 0.010). Tidak terdapat perbedaan bermakna pada D90 HR-CTV (p = 0.077), D2cc bladder (p = 0.077), dan D2cc sigmoid (p = 0.653). D2cc rektum lebih tinggi pada IC+ISBT (p = 0.006), tetapi masih dalam batas toleransi tanpa peningkatan toksisitas bermakna (p = 0.398). Dosis titik A1 dan A2 lebih tinggi pada IC+ISBT (keduanya p < 0.001). OTT brakiterapi tidak berhubungan dengan respons tumor (p = 0.976). Nilai post hoc power adalah 73%. Kesimpulan: IC+ISBT memberikan angka respons tumor yang lebih tinggi tanpa meningkatkan toksisitas akut. Teknik ini layak dipertimbangkan pada pasien dengan residu tumor atau keterlibatan parametrium setelah radiasi eksterna. Penelitian lebih besar diperlukan untuk mengkonfirmasi temuan ini.
Kata kunci: brakiterapi, intrakaviter, interstisial, kanker serviks, dosimetri, respons tumor.


Background: Locally advanced cervical cancer remains a major clinical challenge. Intracavitary brachytherapy (ICBT) is the standard approach after external radiation. However, in cases with residual tumor, asymmetric lesions, or parametrial involvement, intracavitary application alone may provide suboptimal dose coverage. The combined intracavitary-interstitial technique (IC+ISBT) was developed to improve dose distribution to the high-risk clinical target volume (HR-CTV). Local comparative data between the two techniques are limited in Indonesia. Methods: This retrospective observational study included 98 patients with locally advanced cervical cancer who underwent brachytherapy after concurrent chemoradiation at Dr. Cipto Mangunkusumo National General Hospital. Patients were grouped into ICBT (n = 62) and IC+ISBT (n = 36). Outcomes included tumor response (complete Respons/CR vs non-CR), D90 HR-CTV, D2cc doses to the bladder, rektum, and sigmoid, point A1 and A2 doses, acute toxicity, and brachytherapy overall treatment time (OTT). Bivariate analyses were performed using Chi-square/Fisher’s exact test and the Mann-Whitney test. Post hoc power was calculated based on the Chi-square statistic. Results: The IC+ISBT group demonstrated a significantly higher CR rate compared to ICBT (80.6% vs 54.8%; p = 0.010). No significant differences were found in D90 HR-CTV (p = 0.077), bladder D2cc (p = 0.777), or sigmoid D2cc (p = 0.653). Rectal D2cc was higher in the IC+ISBT group (p = 0.006) but remained within tolerance limits and was not associated with increased toxicity (p = 0.398). Point A1 and A2 doses were significantly higher with IC+ISBT (both p < 0.001). OTT was not associated with tumor response (p = 0. 976). The post hoc power for the primary outcome was 73%. Conclusion: IC+ISBT resulted in higher tumor response rates without increasing acute toxicity. This technique may be considered in patients with residual tumor or parametriual involvement after external beam radiotherapy. Larger studies are needed to validate these findings.
Keywords: brachytherapy, intracavitary, interstitial, cervival cancer, dosimetry, tumor Respons.