Impact of overall treatment time and dose escalation on local control in locally advanced cervical cancer

treated by chemo-radiation and image-guided adaptive brachytherapy

Renaud Mazeron# 57608 (abstract 1827)DPD 06. Digital Poster Discussion - GYN

GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6

Background

Image-guided adaptive brachytherapy (IGABT) is becoming a standard in the treatment of locally advanced cervical cancer

Local control rates reported in monocentric series are high, about 90% (Pötter et al., Nomden et al., Mazeron et al.)

Objective: Identifying the prognosis factors for local control in a cohort a patients treated with concomitant chemo-radiation followed by IGABT

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GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6

Material and Methods

Consecutive patientsLocally advanced cervical cancer (IB2-IVA)Curative intentGEC-ESTRO recommendations appliedAt the beginning of our experience, patients with

stage I-II lesions went throughout post radiation hysterectomy. For them, local failure was considered in case of macroscopic remnant (1 cm in width) or in case of local relapse during their follow-up.

In patients treated with definitive radiotherapy, local failure was defined as any relapse in the cervix, vagina, parametium, or uterus during the follow-up.

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GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6

Note: Post radiation hysterectomy

Patients included to warrant consecutive patientsTreated at the beginning of our experience, with

doses lower than nowadays. Important to study dose-response effect.

1cm as cutoff: strong prognosis factor reported in the literature

Prognostic factors were analyzed using a linear regression model. Additional dose / effect correlations were done using the logit model.

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Statistics

GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6

Results

Tumor width at diagnosis (> 5 cm), initial tumor volume (>50 cm3), D90% of the HR-CTV (high risk, > 85 Gy), the HR-CTV volume (> 30 cm3) and overall treatment time (OTT, > 55days) appeared significantly correlated with local control in univariate analysis, but treatment duration remained the only significant factor in multivariate analysis (p=0.022, odds ratio=2.44).

Logit models: positive for OTT, D90 HR and IR-CTV

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GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6

Figure 1

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GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6 7

GUSTAVE ROUSSY Mazeron R ASTRO GYN PD6

Take home messages

OTT remains important with a loss of 0,5% of local control probability beyond 55 days

This is less than reported 10 years ago (1%) but significant

A dose-response for both HR-IR CTV has been shown similar to that demonstrated by Dimopoulos et al. for HDR brachytherapy, supporting the dose escalation concept (see oral presentation by Kari Tanderup)

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If any query, please contact me:

Radiation therapy department

renaud.mazeron@gustaveroussy.fr