Seminar article
Bladder (cancer treatment)
Are nomograms needed in the management of bladder cancer?

https://doi.org/10.1016/j.urolonc.2009.04.020Get rights and content

Abstract

Bladder cancer has a remarkably variable natural history. Noninvasive, low-grade (TaLG) lesions have a propensity to recur but pose little threat to the patient's longevity. Non-muscle-invasive, high-grade (Ta-TIS-T1HG) lesions can be effectively treated with intravesical BCG, but a subset may progress to muscle-invasive and metastatic bladder cancer. Muscle-invasive cancers (T2-T3) are uniformly lethal if inadequately treated, and subsets of patients benefit from perioperative chemotherapy and some may be adequately treated with bladder preservation strategies. The ability to accurately predict this variable natural history is essential to optimize treatment. At each stage of disease, the prognosis is often influenced by multiple parameters (e.g., tumor grade and stage, age, comorbidity) and treatments (e.g., radical cystectomy vs. BCG), and different endpoints are relevant based on the stage of disease (recurrence for TaLG, progression for Ta-TIS-T1HG, survival for T2-T4a). Historically, prediction of these endpoints for decision-making has been accomplished with physician judgment and/or basic decision aids such as risk classification systems. However, such methods of risk estimation are unable to fully account for the complex tumor biology and behavior of bladder cancer, potentially leading to inaccurate predictions and inappropriate treatment assignment. Nomograms are capable of incorporating multiple variables and generating accurate risk estimates tailored to the individual patient which may greatly facilitate patient counseling and treatment selection. Although their use has become more widespread, bladder cancer nomograms remain a relatively nascent field of study, and further development of novel nomograms that can account for all clinical stages of bladder cancer is needed.

Introduction

In the field of urologic oncology, the optimal treatment strategy for an individual patient is one that maximizes oncologic efficacy and survival while minimizing morbidity and any adverse impact on quality of life. However, management decisions are rarely ever straightforward and can be complicated by complex tumor biology, variable treatment approaches, as well as a paucity of definitive data (i.e., from randomized controlled trials) favoring one therapy over another. As a result, consensus on what constitutes optimal treatment can be difficult to reach, often generating controversy and confusion amongst clinicians and patients alike. This is certainly the case with bladder cancer, a heterogeneous disease with a course that varies greatly from patient to patient and requires multiple therapeutic approaches.

Effective patient counseling regarding the merits of alternative treatment strategies depend upon accurate estimation of relevant treatment outcomes (e.g., risk of treatment failure, rate of survival, or the incidence of complications). In this regard, decision aids, such as risk groupings, probability tables, and nomograms, have greatly enhanced our ability to predict endpoints and provide patients the data they require to make informed medical decisions. Nomograms are among the more accurate means of estimating risks and have been shown to surpass other classes of decision aids, including risk groupings, neural networks, or probability tables, in predictive accuracy [1], [2], [3], [4], [5], [6], [7]. In this review, we examine the current status and utility of nomograms in bladder cancer, comparing their predictive capacity against traditional prediction methods and also determining the need for novel nomograms.

Section snippets

Controversies in bladder cancer management

Treatment strategies in bladder cancer can be quite variable, and selection is determined by a combination of tumor-related factors (e.g., stage, grade, size, multifocality, associated CIS, vascular invasion, and histologic subtype), patient-specific characteristics (age, comorbidity, and utilities), as well as molecular markers (p53, pRB, p16, p21) and laboratory tests (cytology or FISH). All of these clinical parameters can impact disease course and determine the risks of tumor recurrence,

The evolution of generating predictions for clinical decision-making

With the lack of conclusive data favoring any treatment over another, physicians and patients alike rely on estimates of outcomes when considering bladder cancer risks and treatment choices. Historically, when a patient has wanted a prediction, physicians relied on their own individual knowledge and experience to provide patients with a prediction of an outcome, such as life expectancy or the chance of treatment success. Decision-making and patient counseling have since evolved with the

The utility of nomograms in bladder cancer

Nomograms demonstrate several advantages over other prediction tools: they incorporate multiple prognostic markers, generate individualized risk estimates, and are presented in an intuitive graphical format that avoids complex calculations. Not only can nomograms assist in basic treatment selection, but by offering highly accurate means of identifying bladder cancer patients at high risk for adverse outcomes (e.g., treatment failure or metastatic progression), they can also facilitate the

Nomogram vs. physician judgment

The current interest in developing nomograms for use in bladder cancer and other diseases is predicated on the assumption that they are superior to traditional methods of risk estimation, which include physician judgment and risk groupings. Before the advent of formal decision aids, management decisions were traditionally based upon physician judgment. In recommending a specific form of therapy to a patient, a clinician presumably believes that relevant outcomes for that treatment modality are

Nomogram versus risk classification

Because individual physician judgment is clearly not an ideal foundation for outcome prediction, many clinicians have turned to formal decision aids for patient counseling. Risk classifications, such as the AJCC TNM staging system or the WHO pathologic grading system, have enjoyed widespread popularity due to their simplicity and become integral to the management of bladder cancer. Traditional risk groupings determine prognosis by assigning patients into categories based on the presence or

Current status of bladder cancer nomograms

Traditional methods of risk estimation may not provide the best predictive accuracy or applicability to individual patients. Undoubtedly, individual clinicians' expert knowledge and advice are still crucial to patient counseling and the measurement of variables used in the prediction process, and risk groupings can certainly be valuable for making general observations about the bladder cancer population as a whole. However, the distinct advantages of nomograms have prompted greater interest in

Future directions for bladder cancer nomograms

Although nomograms currently represent the most accurate means of risk stratification, they do possess limitations which provide the opportunity for research and improvement. To date, no nomogram, or any other prediction method, has been able to predict clinical outcomes with 100% accuracy. The suboptimal predictive accuracy of current nomograms is partly due to the inherent unpredictability of bladder cancer, a heterogeneous disease with a highly variable course. However, there are modifiable

Conclusions

Bladder cancer is a heterogeneous disease with a course and prognosis that can vary greatly from patient to patient. Prediction of tumor behavior in the individual patient is therefore critical to patient counseling and selection of the treatment strategy that optimizes survival and quality of life. Assessment of the risk of disease recurrence, progression, or mortality in bladder cancer patients by traditional prediction methods, such as physician judgment or risk classification systems, can

References (24)

  • D.J. Sargent

    Comparison of artificial neural networks with other statistical approaches: Results from medical data sets

    Cancer

    (2001)
  • S.F. Shariat et al.

    Nomograms provide improved accuracy for predicting survival after radical cystectomy

    Clin Cancer Res

    (2006)
  • Cited by (16)

    View all citing articles on Scopus
    View full text