Background:Two million people in the UK had a cancer diagnosis at the end of 2008. Understanding the number of people diagnosed with cancer with and without health needs is valuable information that can be used to inform service planning, treatment provision and support for people at the right time in the right place as demand grows over time.Methods:Using available data and clinically led assumptions about patient need and outcomes, we make indicative estimates. We quantify, for three common cancers, the number of people in each of the five main identified phases of the cancer care pathway.Results:Estimates are provided for each phase of the pathway for breast, colorectal and lung cancers. We estimate that there are nearly 575 000 women a year with breast cancer in the care pathway at some point in the year, 8% are in the rehabilitation phase and 4% in the progressive illness phase. This compares to nearly 270 000 with colorectal and around 95 000 with lung cancer.Conclusion:Using readily available data, we estimate the numbers of patients with different health needs. These numbers could inform the targeting of resources for service providers.