Is cancer so “uncurable” we only hope to extend the patient’s life and not cure it completely?
In: Biology
A lot of cancers are very curable if discovered early. Those survival year rates are a way to measure how aggressive the cancer is, as well as how It responds to the treatment.
If you survive 5 years, its likely that your cancer is less aggressive/responds well to treatment
As a bonus, the window of time to consider someone cancer free is also 5 years, because every cancer has a chance to return even after treatment, but If after 5 years It hasn’t returned, the odds of It ever returning become very small
Yes, cancer is rarely “curable.” In many cases it can only be treated, managed, until by stroke of bad luck or inevitability (cancers mutate and “evolve” and get stronger, acquire the ability to evade the immune system, spread and generally get more nasty as time goes on) they tend overwhelm the body.
Of course if you catch it early enough you can hope to eradicate every last cancer cell, and then you’re cured. But if even one cell remains, it can come back stronger and deadlier. Once they spread, either regionally or distantly (metastasis), the probability of getting every last cell plummets.
There’s a great [Kurzgesagt video](https://www.youtube.com/watch?v=uoJwt9l-XhQ) on how cancers “evolve” and get stronger.
Simplification: cancer treatments rarely kill / remove all the cancerous cell. Some are dislocated or are already roaming your system. If those cells don’t “stick” in 3 to 5 years, you are considered cured of that particular cancer.
I mean, you can’t exactly get 50 year survival rates before 50 years have passed. Using some small number as the gold standard lets you compare drugs in a time frame that makes sense. If a drug is effecting 3 and 5 year rates then cool, use that drug, 30 years later we can do the actual study to see how it goes on 30 years. We aren’t going to start on the 30 year trials before putting it out!
A lot of answers miss the point. Cancer is an older person’s disease, and curing cancer in a 75 year old and extending their life by 5 years, but an older persons body might not withstand the treatment itself.
Since cancer comes from mutations that change the cell workings, and those errors are passed on through that cell lineage, unless you are able to kill every cell of that lineage, the cancer may come back.
And since those mutations can happen for many reasons, some hereditary and some environmental, you may have another cancer happening after the first was “cured” (all cancerous cells destroyed) because you already have conditions that facilitate those mutations.
It is very hard to measure small amounts of cancer. So we can not easily say if they are cured or not. Even after 10 years with regular checkups there have been relapses. Another issue is that cancer treatment is generally very bad for the body. It is not uncommon for doctor to cure the cancer only for the patient to die from the treatment a bit later. So we avoid saying things like the patient is cured from cancer. Instead we measure how long a patient lived after they were diagnosed, or after they started treatment. This is far more accurate then any other measurement. Although it is far from perfect.
Another factor to consider is that survival rates of 5 years, etc, are often based on studies that are nearly 10 years old. Cancer treatments are improving at a very fast pace, and cancers that had relatively low 5 year survival rates 10 years ago often have much better survival rates if you were to look at newer cases.
Cancer research statistician here: some answers here are in the ballpark, some completely missing the mark. An exact answer is complex. In short, those rates or probabilities are given because the studies used to generate them are designed with 3- or 5-year survival in mind.
In many cancers, those endpoints are chosen because we may have data to suggest that if you survive to 3 years, then the probability of surviving long term after that is really good. If your disease is going to respond to a treatment, then it likely will in the first 3-5 years. If you’re alive after that, then outcomes stabilize quite a bit.
Further, we design our clinical trials using those endpoints to be able to compare new treatments to historical data. Those endpoints might be considered the standard set by the FDA as to how to estimate efficacy for a specific cancer. We then take the data from those studies to create prediction models or clinical nomograms which are tools that will allow a doctor to talk through with their patient what is their 3 or 5 year survival probability, something that pretty much everyone can easily digest and interpret.
Ideally, we would want to be able to tell someone their long-term survival chances. But that takes a long time conduct studies around – and clinical research is already a slow process. In some cases 3-5 years isn’t very helpful, and so cancer trials may utilize other surrogate endpoints to try to assess endpoints more quickly (objective response rate, event free survival, progression free survival, etc.) that should correlate with long-term survival.
Most things in medicine are merely managed rather than “cured.” Cancer is unique because in theory if you remove all the cancerous cells you would be cured. Unfortunately there’s very few cancers that can be detected and completely removed from your body. Later stages of cancer mean that cancerous cells have spread beyond the first tumor, at which point it’s basically whack-a-mole trying to stop cancer and keep the patient alive.
Modern technology is pretty incredible however, and a bunch of recent advances have made many more cancers and stages survivable.
Latest Answers