3DCRT Treatment Shows Better Survival for Cervical Cancer

In the late 1990s, 3-dimensional conformal radiation therapy (3DCRT) emerged as a preferred treatment for gynecologic malignancies because it provided better and more precise target coverage and significantly reduced the volume of radiation-exposed bladder and bowel. Yet, its superiority to 2-dimensional radiotherapy (2DRT) has not been well established. In a new study, researchers in Taiwan investigated the relative benefits of 3DCRT and 2DRT in patients with cervical cancer. They reported results online in ISRN Oncology [DOI:10.1155/2013/729819].

Using data from the 2005 to 2010 National Health Insurance Research Database provided by the National Research Institutes in Taiwan, the researchers conducted a large-scale, nationwide, controlled, cohort study. Participants were initially classified as having cervical cancer according to the International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) 180, and this clinical diagnosis was confirmed histopathologically or cytologically. Between January 2005 and December 2010, the researchers identified 8134 patients with newly diagnosed cervical cancer. After excluding patients without metastasis, local recurrence, or surgical treatment before radiation therapy, the final cohort included 776 patients who received 2DRT (n=132) and 3DCRT (n=644). The primary end point was 5-year survival rate, which was measured from diagnosis of cervical cancer to the time of death.

Statistics show that cervical cancer is the second most frequent cancer among women worldwide and the most common cancer among women in Africa, Asia, and South America. After adjustment for age, diabetes, hypertension, coronary heart disease, hyperlipidemia, side effects, urbanization level, geographic region, and enrollee category in the 5-year follow-up period, the hazard ratio was 1.82 (95% confidence interval, 1.16-2.85; P=.009).

The 5-year survival rate was significantly better in the 3DCRT group compared with the 2DRT group (82.3% vs 73%, respectively; P=.007). The researchers also looked at the 5-year cumulative survival rate of 3DCRT and 2DRT after stratifying the cervical cancer patients into a low-risk group (n=221) and high-risk group (n=555). Criteria used to stratify the cohort included >55 years of age, hypertension, diabetes, coronary heart disease, and hyperlipidemia. The 5-year cumulative survival rate for the 2-risk groups was 86.5% for 3DCRT and 78% for 2DRT (P=.05). The incidence trend of side effects was significantly lower in the 3DCRT group compared to the 2DRT group (31% vs 23%; P=.04). The researchers attributed this as 1 reason why survival rate was better in the 3DCRT treatment group.

The researchers noted several study limitations including that cervical cancer diagnosis, and many other comorbid conditions, was completely dependent on ICD codes. Cancer stages were not a factor because this information was not available in the database. Furthermore, several studies have reported that diabetes could be a factor influencing survival.

In summary, the investigators found that 3DCRT compared to 2DRT leads to a better overall survival rate in cervical cancer patients. For cervical cancer patients with more comorbidities, the survival rate is poorer. The researchers recommended that strategies to reduce the risk of comorbidity should be assessed.