The Prognostic Nomogram in Platinum-Resistant Ovarian Cancer: How to Develop and Validate?

Dr. Lee et al. reported “Development and validation of a prognostic nomogram for overall survival in patients with platinum-resistant ovarian cancer treated with chemotherapy”, on Eur J Cancer (1). Via the data from chemotherapy-only arm in AURELIA and randomized cases in CARTAXHY trial as training cohort, Dr. Lee created a nomogram to predict the prognosis in ovarian cancer. This prognostic nomogram was developed and generated by the pretreatment characteristics such as patients’ performance, tumor size, or CA-125, etc., under multivariable proportional hazards models. Further, Dr. Lee applied their nomogram in other two large-scale data, bevacizumab-chemotherapy arm of AURELIA and PENELOPE trial as validation cohort, to calibrate the performance. They selected six significant predicting markers including patients’ performance, intra-abdominal ascites, size of largest tumor, serum CA-125, platinum-free interval, and platinum-resistance status. Surprisingly, we can notice rather powerful stratification of overall survival (OS) in the patients with platinum-resistant ovarian cancer. Not only training cohort but also validation cohort, Dr. Lee’s nomogram can discriminately analyze OS in different prognosis groups. In training cohort (chemotherapy-only arm in AURELIA and randomized cases in CARTAXHY), the median OS of good, intermediate, and poor prognosis groups were 25.3, 15.2, and 7.4 months, respectively. As to validation cohort, PENELOPE (C-statistic 0.59) and bevacizumab-chemotherapy arm of AURELI (C-statistic 0.67), the median OS were 18.5, 10.3, 5.8 months and 26.7, 13.8, 10.0 months in the good, intermediate and poor prognosis groups. Their conclusion revealed that their nomogram may effectively predict or counsel the prognosis and survival status for the patients of platinum-resistant ovarian cancer. The current study is interesting and worthy of further discussion. Firstly, these authors mainly developed several nomograms for different subtypes of ovarian cancer and other cancer, such as progression-free survival and overall survival in platinum-sensitive recurrent ovarian cancer (2), advanced breast cancer (3), metastatic gastrointestinal stromal tumor treated with imatinib (4). Therefore, they had good experiences to create a prediction tool. Nomogram, or called nomograph, is a graphical and mathematical calculating method to create a diagram reaching estimated graphical computation. A set of n scales, and one for each variable in an equation, were included in the nomogram. Knowing the values of n-1 variables, the value of the unknown variable can be found; alternatively, the relationship between the unfixed ones can be studied by fixing the values of some variables. It is widely used in chemistry, aeronautics, astronomical calculations, and oncology, etc. In the field of oncology, it is frequently used to predict cancer survival mainly because of reducing statistical Editorial Commentary