Reporting of Cancer Stage at Diagnosis
Measure: Reporting of cancer stage at diagnosis (Collaborative Staging) for stageable breast, cervix, colorectal, lung and prostate cancers
As of this Report:
Stage capture rates using the Collaborative Staging (CS) data collection system exceed the provincial target of 90% completeness for breast, prostate, colorectal, lung and cervix cancers. When other types of cancer are considered, the overall stage capture rate for all stageable cancer cases in 2016 was 52%, a rate that is stable compared to the previous year. While both data from CS and clinician-staged data are collected by Cancer Care Ontario, the former is derived directly by Cancer Care Ontario staging staff using Tumour, Node and Metastasis Staging System (TNM) and prognostic data. The rates reported under this indicator do not reflect physician staging practice in the clinical setting but rather the completeness of stage data collection within the provincial cancer registry.
What is cancer staging?
- Staging describes the extent or severity of a person’s cancer, based on the size and/or extension of the original (primary) tumour and how far it has spread in the body .
- Almost all cancer patients begin their involvement with the cancer system through a series of diagnostic tests. These likely include imaging and, in many cases, removal of tissue or cells for examination (biopsy). These tests allow the nature and extent of the cancer to be determined.
- Stage at diagnosis can be described as Stage 0 (in situ), Stage I and II (localized), Stage III (regional) or Stage IV (distant spread or metastasized). To date, in situ cases have not been staged by the provincial cancer registry.
- A stageable case is one for which a staging schema exists (e.g., TNM and CS), a patient health record is available and the required data elements are documented in that record.
- An unknown stage is the result of either limited stage workup and/or limited documentation within the patient record.
What is the Collaborative Staging data collection system and how is it different from Tumour, Node and Metastasis staging system data?
Measure: Reporting of cancer stage at diagnosis (Collaborative Staging) for all stageable cancer
As of this Report:
- The TNM staging system is promoted by the American Joint Committee on Cancer (AJCC) and the International Union against Cancer (UICC). It uses information about tumour growth (T), regional lymph node involvement (N) and the presence of distant metastases (M) to determine a patient’s stage of disease at diagnosis .
- CS is a stage data collection system that uses an algorithm to combine elements of TNM to derive a stage group . It has been the Canadian standard since 2004. Beginning with the 2018 diagnosis year, all Canadian provincial and territorial cancer registries will move to directly coded TNM, using the AJCC TNM 8th Edition.
- In more recent years, prognostic factors that have a bearing on survival and treatment outcomes (such as biomarkers) have been incorporated into both TNM and CS.
- “Unknown Stage” is assigned by the CS algorithm when there is insufficient information to assign a category.
- “No Stage” is the term assigned to cases for which no hospital record is available for review. This can occur when (a) there is only a physician office record or a private lab report, (b) the hospital record is for a facility that is not part of the CS program or (c) the diagnosis year was closed off before the Ontario Cancer Registry (OCR) stage team could complete all cases.
- The OCR captures stage at diagnosis for breast, lung, colorectal and prostate cancers using CS for cancers diagnosed from 2010 to the present. Cervical cancers have been captured by the OCR using CS since the 2011 diagnosis year.
- Regional Cancer Centres (RCCs) submit TNM stage data to Cancer Care Ontario for those cancers not staged at Cancer Care Ontario using CS. However staging data from RCCs only captures cases referred to an RCC for diagnosis and first course of treatment.
Cancer diagnosis means accuracy of that diagnosis and knowing exactly what the next steps will be. There can be no doubt because as soon as those words are spoken a different journey in life begins.
– Laurie P., Patient/Family Advisor
What do the results show?
Collaborative Staging rates have improved for breast, colorectal, lung and prostate cancers, but the overall cases with Collaborative Staging have decreased (Figures 1, 2 and 3).
- The number of stageable cases in Ontario increased 6%, from 63,198 in 2010 to 66,430 in 2016. The ratio of stageable cancers to incident cases, however, has remained relatively stable (Figure 1).
- Beginning in 2014, Cancer Care Ontario ceased capturing CS stage data for non-cervix gynecologic cancers, melanoma and thyroid cancer. Primarily as a result of this change, the overall CS stage capture rate decreased in 2014 (Figure 2).
- With the OCR’s new focus on staging breast, colorectal, lung and prostate cancers in 2014, an increase was observed in the stage capture rates for those 4 sites, which now exceed the provincial aim of 90% completeness. The highest rate in 2016 was for breast and lung cancers (95%) (Figure 3).
Breast, cervical, colorectal and prostate cancers had consistent stage distribution from 2010 to 2016. The exception is lung cancer, for which Stage I cases have increased over time (Figures 4 to 8).
- The stage distribution of breast cancer varied little over the 7 years examined, with approximately 80% of cases diagnosed at early Stage I and II (Figure 4).
- Similarly, from 74% to 80% of cases for prostate cancer were in the first 2 stages (Figure 8). This is in contrast to colorectal cancer, for which approximately 50% of cases were Stage I and II (Figure 6). The stage distribution for prostate and colorectal cancers has been relatively consistent from 2010 to 2016.
- Cervical cancer stage distribution was fairly consistent across years. However, due the smaller cohort, even minor shifts in the number of cases diagnosed can result in greater change in stage distribution (Figure 5).
- The Stage IV distribution of all lung cancer cases decreased from 56% in 2010 to 46% in 2016. However, Stage IV still remained the most common stage at diagnosis for lung cancer (Figure 7). The greater distribution in late stage cancers is indicative of the issues preventing early detection, specifically asymptomatic disease and the lack of screening programs .
- Stage distribution rates in Ontario for breast, colorectal, prostate and lung cancers are generally consistent with other jurisdictions across Canada .
Why is this important to Ontarians?
- Clinical stage at diagnosis helps physicians to plan appropriate treatment and to determine the likely outcome or course of the disease [2, 5].
- From a system performance perspective, population-level stage at diagnosis facilitates cancer surveillance and healthcare planning. Knowing the distribution of cancer stage allows cancer agencies to better evaluate the effectiveness of screening programs and the prioritization of resources for those disease sites that have a higher incidence of advanced disease .
- Linking the stage of cancer with outcome and treatment data provides valuable information, allowing the cancer system to assess the quality of cancer care and identify new ways to improve the delivery of that care. For example, this Cancer Screening Quality Index (CSQI) provides performance information on the following indicators (which depend on accurate stage information):
Find out more
For more information on stage capture, please see Cancer Care Ontario’s website.