1. Introduction
Cervical
cancer is the fourth most commonly diagnosed cancer and the fourth
leading cause of mortality among women worldwide. There were over
570,000 new cases annually and over 311,000 deaths in 2018 globally
[1]. More than two-thirds of the patients are diagnosed with locally
advanced cervical cancer (LACC) [2].
Concurrent chemoradiotherapy
(CCRT) can lead to good prognosis for LACC [3], and the
brachytherapy as a part of standard treatment regimen has further
improved local control and overall survival, but the chemoradiotherapy
resistance and local relapse also occur among 40% of LACC patients
[4, 5]. Early treatment response correlates to tumor response and
survival [6].
Hematologic
toxicity is the most common acute side effect of CCRT, which affect
treatment efficacy and sometimes can be life-threatening [7].
Pretreatment prediction of early tumor response, survival, and
hematologic toxicities may assist physicians to adjust radiotherapy
planning and further improve the quality of life.
Previous studies demonstrated that
the predictive efficacy of
clinicopathological model for
treatment outcomes is limited in LACC [8, 9].
The therapeutic effect can be
markedly different even in the same clinical stage. Currently,
radiomics, a technique that can extract high-throughput quantitative
features from imaging such as CT, PET, and MRI, has emerged as a
promising tool for the assessment of treatment outcomes [10, 11].
Radiomics can reflect the tumor intrinsic properties and can be used as
independent predictors of survival outcome with higher predictive
ability than traditional clinical parameters alone [12, 13].
Radiomics has been found to be related to lymph node metastases [14,
15], treatment response [16-18], patient survival [19], and
tumor recurrence [16, 20] for cervical cancer patients [21]. So
far as we know, there are no studies to investigate the radiomics
predictive ability of CT images from radiotherapy planning system.
Additionally, myelosuppression is
the most common toxicity in pelvic radiotherapy with the Grade 3 or
higher hematological toxicities of more than 30% [22].
Bone marrow is the most
radiosensitive pelvic organ, and approximately 40% of the total body BM
reserve lies within the pelvic bones, especially pelvis and sacral
vertebrae, which always are within the irradiated fields [23]. The
individual differences of the radiation-induced hematologic toxicities
caused even by the similar treatment regimens. Previously, radiomics was
used to quantify lumbar and femoral mineral loss [24], mineral bone
density, and osteoblast activity [25]. Treatment planning CT-based
radiomic features of pelvis and sacral vertebrae may be able to predict
the hematologic toxicities.
Therefore, we retrospectively examined radiotherapy planning CT images
to establish radiomic models for predicting tumor complete response
(CR), 5-year overall survival (OS) as well as hematologic toxicities
(leucopenia
and hypohemoglobin) in LACC patients. We also compared the prediction
performance of clinicopathological parameters and radiomic features to
further construct a combined model, aiming at better prediction of
clinical endpoints in LACC.