Why US cancer registries need to be modernized to help us better understand cancer.
I first heard about the National Cancer Institute's SEER (Surveillance, Epidemiology, and End Results) Registry in 2017 at Living Beyond Breast Cancer's annual conference for people with metastatic breast cancer. A cancer advocate, Katherine O'Brien, had put together an online petition for the Metastatic Breast Cancer Alliance asking that data collection be modernized. I was surprised when a couple of simple questions dramatically revealed whose stage 4 cancer was being "seen" by SEER and whose was not.
Hint: The vast majority was not being counted.
The reasons for this lack of data are complicated, but mostly come down to a lack of financial resources. SEER has been counting cancer by incidence, initial treatment, and mortality since 1973 in select populations of certain states. From this data, we receive the statistics about cancer from organizations like the American Cancer Society and the American Society of Clinical Oncology. The SEER registry provides a lot of interesting data that can be tracked by cancer type, stage at diagnosis, age, race, etc.
What you can't do is track recurrence information or know with certainty, within a few thousand individuals, how many people are living with metastatic breast cancer (or any type of metastatic cancer).
That's because SEER doesn't track recurrence information. I count in SEER because my diagnosis was stage 4 from the start, but most of my metastatic breast cancer friends do not. They don't count until they die, and only then if the death certificate lists breast cancer as the cause.
I think about this every time I see news about updated cancer statistics. I always have questions:
How can you know us if you don't count us? Estimates tell us that about 6% of the people with metastatic breast cancer were stage 4 from the start, which means the vast majority were once diagnosed at earlier stages. This is an accepted statistic, recently repeated here by the American Cancer Society. But what about the rest of the people with metastatic breast cancer - do we know much, statistically, about them? For me, the five-year survival statistics in breast cancer are particularly telling. The current data say that 89.9% of people diagnosed with breast cancer are alive at five years, but because recurrence data are not collected we don't know how many of that 89.9% are living with stage 4 breast cancer. Though factually correct, the data misleads us. Since SEER doesn't track cancer recurrences, including metastatic spread, a person who was stage 2 is always stage 2, even if she is alive at five years with metastatic progression that will eventually cause death.
How do we know what's working if we're not tracking patients? One of the shortcomings of the SEER Registry is that because it doesn't track recurrences, and therefore doesn't reveal when patients recur with metastatic disease nor how long they live, the data collected and shared does not provide a complete picture. For instance, it can't tell us what percentage of people diagnosed with early-stage breast cancer progress to metastatic breast cancer. The American Society of Clinical Oncology is precise in that regard, stating: "More research is needed to determine how many people with non-metastatic breast cancer later develop metastatic breast cancer." If patients were counted by cancer specifics, including recurrence and treatment over time, we'd have a clearer picture of what is actually happening with breast cancer. This method of not following patients made sense when SEER first started collecting data, but the data collection needs to take advantage of modern technology. I was recently on Capitol Hill with Metavivor asking for Congress to make this better data collection a reality.
Is this a case of bad data in/bad results out? If you don't know how many people are living with metastatic disease, how many early-stage breast cancer patients develop metastases, when their cancer became metastatic, or how long they've lived with metastases, then you're missing crucial pieces of information. The statistics matter because they influence what kind of research gets funded, help oncologists know what to say when a patient asks about her chances of cancer returning, and help those already living with metastatic breast cancer by counting them in a meaningful way.
Good research, life-saving research, demands the best data. The American Cancer Society report showed some alarming news about breast cancer, including the fact that the decline in the death rate has slowed over time. Since estimates tell us that about 42,000 women and men in the United States will die from breast cancer this year - a number that has remained largely unchanged for decades - the clock on better data collection is ticking.