MRI, PET/CT combo offer optimal outcome for cervical cancer

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Pretreatment MRI and PET/CT for cervical cancer may direct more women to optimal therapy choices and spare many women potential long-term morbidity and complications of tri-modality therapy (surgery followed by chemoradiation), according to a study performed at the Institute for Technology Assessment in Boston.

“In recent years, optimal treatment choices for cervical cancer have been increasingly tailored to the extent of disease, necessitating parallel improvement in algorithms for pre-treatment evaluation” wrote the authors of the study, published in the March issue of the American Journal of Roentgenology. “Because both overestimation and underestimation of disease extent can result in adverse patient outcomes, accurate staging is critical for optimizing patient outcomes.”

An interdisciplinary team of investigators developed a decision-analytic model to determine the value of pretreatment imaging with MRI and/or PET/CT in patients with International Federation of Gynecology and Obstetrics (FIGO) Stage IB cervical cancer.

“Stage IB cervical cancer, in the absence of pre-treatment imaging, is treated with surgery. As surgery cannot completely resect the cancer in many of these patients, they receive post-surgical chemoradiation, i.e. tri-modality therapy,” noted Pari Pandharipande, MD, lead author of the study. “The goal of pre-treatment imaging is to identify these patients noninvasively, spare them surgery and have them treated with chemoradiation alone.”

The research group developed a decision-analytic model to predict outcomes for a hypothetical patient cohort with FIGO IB cervical cancer who underwent pre-treatment MRI, PET/CT, MRI and PET/CT, or no further imaging (direct pursuance of surgery).

Model results of cervical cancer imaging strategy according to clinical outcome of interest. Graph shows triage to correct primary treatment was highest with PET/CT (89.27 percent) and lowest with MRI (68.21 percent). Image and caption courtesy of the American Roentgen Ray Society.

Their model incorporated imaging performance, underlying parametrial extension and lymph node involvement, surgery and chemoradiation treatment options, and survival penalties from incorrect assessment of disease extent.

The scientists compared three outcomes were compared: 5-year overall survival, percentage of patients receiving correct primary therapy, and percentage of patients spared tri-modality therapy. They then performed sensitivity analysis to assess the effects of model uncertainty on outcomes.

Study results showed that while imaging does not improve survival, PET/CT resulted in the highest percentage of patients receiving correct primary therapy (89 percent) and use of both MRI and PET/CT spared the most patients of tri-modality therapy (95 percent). 

“Pre-treatment imaging can triage patients to optimal primary treatment choices that minimize the risk of long-term complications and morbidity while preserving chances for survival,” said Pandharipande. “Because both over- and underestimation of disease extent can result in adverse patient outcomes, determining the extent of disease accurately up front is critical. For example, when patients are subjected to pelvic surgery, and then are radiated in the same operative field, complication rates can increase by a substantial percentage, as compared to if they were simply treated with surgery alone or chemoradiation alone. Our study shows how pre-treatment imaging may improve chances of correctly receiving surgery or chemoradiation instead of both.”

The authors noted that MRI and PET/CT imaging are expensive; however, long-term consequences of tri-modality therapy can severely affect long-term quality of life and are also expensive. They advocated further study of long-term consequences to more precisely consider the cost implications of upfront MRI and PET/CT. 

“Our results underscore the need for further investigation in specific areas of cervical cancer outcomes, particularly for evaluation of quality-of-life and cost implications of therapy choices and their attendant complications,” they wrote. “Such data would enable calculation of quality-adjusted life expectancy and lifetime costs consequent to each imaging strategy, critical goals toward identifying the most clinically and cost-effective strategies across an average patient population with early cervical cancer.”