Tumor-specific outcome of metachronous uterine malignancy after pelvic irradiation for cervical cancer

Risk of Secondary Malignancies After Pelvic Radiation: A Population-based Analysis

Background and objective

Radiation therapy has increasingly been used in the management of pelvic malignancies. However, the use of radiation continues to pose a risk of a secondary malignancy to its recipients. This study investigates the risk of secondary malignancy development following radiation for primary pelvic malignancies.

Methods

A retrospective cohort review of the Surveillance, Epidemiology, and End Results database from 1975 to 2016 was performed. Primary pelvic malignancies were subdivided based on the receipt of radiation, and secondary malignancies were stratified as pelvic or nonpelvic to investigate the local effect of radiation.

Key findings and limitations

A total of 2 102 192 patients were analyzed (1 189 108 with prostate, 315 026 with bladder, 88 809 with cervical, 249 535 with uterine, and 259 714 with rectal/anal cancer). The incidence rate (defined as cases per 1000 person years) of any secondary malignancies (including but not limited to secondary pelvic malignancies) was higher in radiation patients than in nonradiation patients (incidence rate ratio [IRR] 1.04, confidence interval [CI] 1.03-1.05), with significantly greater rates noted in radiation patients with prostate (IRR 1.22, CI 1.21-1.24), uterine (IRR 1.34), and cervical (IRR 1.80, CI 1.72-1.88) cancer. While the overall incidence rate of any secondary pelvic malignancy was lower in radiation patients (IRR 0.79, CI 0.78-0.81), a greater incidence was still noted in the same cohorts including radiation patients with prostate (IRR 1.42, CI 1.39-1.45), uterine (IRR 1.15, CI 1.08-1.21), and cervical (IRR 1.72, CI 1.59-1.86) cancer.

Conclusions and clinical implications

Except for localized cervical cancer, when put in the context of median overall survival, the impact of radiation likely does not carry enough weight to change practice patterns. Radiation for pelvic malignancies increases the risk for several secondary malignancies, and more specifically, secondary pelvic malignancies, but with a relatively low absolute risk of secondary malignancies, the benefits of radiation warrant continued use for most pelvic malignancies. Practice changes should be considered for radiation utilization in malignancies with excellent cancer-specific survival such as cervical cancer.

Patient summary

The use of radiation for the management of pelvic malignancies induces a risk of secondary malignancies to its recipients. However, the absolute risk being low, the benefits of radiation warrant its continued use, and a change in practice patterns is unlikely.

Secondary ovarian cancer after external beam radiotherapy for nonovarian pelvic malignancy

OBJECTIVE

To examine characteristics and survival of patients who developed secondary ovarian cancer after external beam radiotherapy (EBRT) for a prior nonovarian pelvic malignancy.

METHODS

This is a population-based retrospective cohort study, querying the Surveillance, Epidemiology, and End Result program from 1975 to 2016. 167,269 women who received EBRT for 7 malignancies (anus, rectum, bladder, cervix, uterus, vulva, or vagina) were examined to identify subsequent secondary ovarian cancer diagnosis after EBRT. Then, within the ovarian cancer cohort (n = 147,618), characteristics and survival of patients with secondary ovarian cancer after EBRT were compared to those with ovarian cancer who did not receive prior EBRT.

RESULTS

Following EBRT for a pelvic malignancy, 215 (1.3 per 1000) patients developed secondary ovarian cancer. Among those, the most frequent prior malignancy was cervical cancer (45.6%), followed by rectal cancer (20.9%). The median time from prior EBRT to secondary ovarian cancer was 8.8 years (interquartile range, 2.8-14.5). In multivariable analysis, patients with secondary ovarian cancer after EBRT were more likely to be older, and have a recent year of diagnosis, but less likely to have early-disease compared to ovarian cancer patients without prior EBRT (all, P < 0.05). In weighted model, patients with secondary ovarian cancer after EBRT had decreased overall survival compared to those with ovarian cancer without prior EBRT (5-year rates, 19.6% versus 39.9%, hazard ratio 1.62, 95% confidence interval 1.43-1.85). Similar association was observed in ages <70, ≥70, White, non-White, early-disease, and advanced-disease in sensitivity analyses.

CONCLUSION

Radiotherapy-related secondary ovarian cancer may be associated with decreased overall survival.

Prognostic Model for Predicting Overall and Cancer-Specific Survival Among Patients With Cervical Squamous Cell Carcinoma: A SEER Based Study

BACKGROUND

Cervical squamous cell carcinoma (CSCC) is the most common histological subtype of cervical cancer. The purpose of this study was to assess prognostic factors and establish personalized risk assessment nomograms to predict overall survival (OS) and cancer-specific survival (CSS) in CSCC patients.

METHODS

CSCC patients diagnosed between 1988 and 2015 were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate Cox proportional hazard regression models were applied to select meaningful independent predictors and construct predictive nomogram models for OS and CSS. The concordance index (C-index), calibration curve, and receiver operating characteristic (ROC) curve were used to determine the predictive accuracy and discriminability of the nomogram.

RESULTS

A total cohort (n=17962) was randomly divided into a training cohort (n=11974) and a validation cohort (n=5988). Age, race, histologic grade, clinical stage, tumor size, chemotherapy and historic stage were assessed as common independent predictors of OS and CSS. The C-index value of the nomograms for predicting OS and CSS was 0.771 (95% confidence interval 0.762-0.780) and 0.786 (95% confidence interval 0.777-0.795), respectively. Calibration curves of the nomograms indicated satisfactory consistency between nomogram prediction and actual survival for both 3-year and 5-year OS and CSS.

CONCLUSION

We constructed nomograms that could predict 3- and 5-year OS and CSS of CSCC patients. These nomograms showed good performance in prognostic prediction and can be used as an effective tool to evaluate the prognosis of CSCC patients, thus contributing to clinical decision making and individualized treatment planning.

Second primary uterine malignancies after radiation therapy for cervical cancer

PURPOSE

Radiation exposure has long been established as a risk factor for cancer development. The purpose of this study is to assess the risk of uterine malignancy in patients previously treated for cervical cancer with radiation therapy.

METHODS

A population-based cohort of 9092 patients diagnosed with cervical cancer who did not undergo surgery and received radiation therapy between 1973 and 2008 was identified from the Surveillance, Epidemiology and End Results Program database (SEER 9). Patients in this cohort who developed endometrial cancer after treatment of cervical cancer were identified. 55,140 patients with endometrial cancer were also identified. The distribution of the different histologic types of endometrial cancer was determined for each of these cohorts.

RESULTS

54 patients (0.6%) were diagnosed with an endometrial cancer more than 12 months after diagnosis of cervical cancer. The average latency to endometrial cancer diagnosis was 160 months, with a range of 14-374 months. The average age of cervical cancer diagnosis was 52 years and the average age at subsequent endometrial cancer diagnosis was 66 years. Only 40% of the endometrial cancers diagnosed following treatment of cervical cancer were endometrioid. The majority were clear-cell adenocarcinomas (42%), 9% were carcinosarcomas and 5.5% were leiomyosarcomas. Of the 55,140 endometrial cancer patients in the database, a vast majority were endometrioid adenocarcinomas (91%), and only 2.3% clear-cell adenocarcinoma, 2.3% carcinosarcoma and 0.5% leiomyosarcoma. The difference in histologic type distribution between these two cohorts is highly significant (p < 0.01).

CONCLUSION

A small proportion of women who receive radiation for cervical cancer go on to develop endometrial cancer. These are predominantly of the more aggressive histologic types when compared to primary endometrial cancers. The latency from cervical cancer diagnosis to endometrial cancer diagnosis is over a decade. In a patient who still has a uterus after receiving pelvic radiation, vaginal bleeding should be investigated.