What Survival Rate Really Means With Cancer

Doctor showing information to a senior man about survival rates

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Survival rate is defined as the percent of people who survive a disease such as cancer for a specified amount of time, but may be presented in a number of different ways. Survival rates does not indicate if a cancer is cured or if treatment is completed. Survival rates are also statistics looking at a broad range of people. They do not necessarily predict how an individual with a particular subtype of cancer will do. Learn about the common definitions describing survival with cancer, and the limitations of statistics.

Definitions

There are a number of different terms used to describe survival with cancer, and these can be confusing when looking at information about your own disease. The different terms tend to be used in different settings and with cancers that have different prognoses.

Survival Rates

Survival rates are a statistic that describes how long an "average" person with cancer will survive for a particular amount of time. Survival rates may give as 1-year survival, 2-year survival, 5-year survival, and so on. For example, if the 5-year survival rate for a particular cancer is 34%, this means that 34 out of 100 people initially diagnosed with that cancer would be alive after 5 years.

The term survival rate (especially 5-year survival) is often used when a significant number of people survive with the cancer for a period of time, for example, with breast cancer.

Median Survival

Another term that is often used when talking about survival rates is median survival. Median survival time is the amount of time after which 50% of people have died, and 50% are still alive. Many clinical studies report median survival rather than survival rate, especially in advanced cancers. For example, with metastatic cancer a treatment that extended life for 15 months (had a much better median survival) would not necesarly be seen by looking at survival rates (the two groups may have similar 5-year survival rates though the group treated survived more than a year longer.

Overall Survival (OS)

Overall survival (OS) is another term often used in reference to treatments for cancer. It refers to the time which begins at diagnosis (or at the start of treatment) and up to the time of death. It is usually used as an indication of how well a treatment works.

Progression-Free Survival (PFS)

Progression-free survival (PFS) is a term often used in clinical trials evaluating new drugs and treatments. It refers to the amount of time between when a treatment for cancer begins, and when cancer progresses or death occurs.

Disease-Free Survival

Disease-free survival is a measure of the number of people who are expected to be free from cancer for a particular amount of time. This is also sometimes referred to as "relapse-free survival." Note that overall survival includes both those who are surviving without any evidence of cancer and those who are surviving but still have cancer present in their body.

The term disease-free survival might be preferable when looking at the effects of treatment with a cancer that tends to recur after treatment. This is particularly true with breast cancer, in which late recurrences are common. If a drug reduced the risk of recurrence, but women still lived for, say three years, after their recurrence, the survival rates may not change. But a drug that reduced the risk of recurrence would show a superior disease free survival rate.

Cause-Specific Survival

Cause-specific survival is an important term in clinical studies and refers to the number of people surviving particular cancer after a period of time. An example is the easiest way to describe this. Whereas overall survival from lung cancer includes not only those people who die from lung cancer, but also heart disease, other cancers, and any other condition, cause-specific survival refers to only the likelihood that someone would survive lung cancer alone. This is important in evaluating potential treatments. A theoretical strong drug which damages the heart may increase cause-specific survival from lung cancer but could actually lower overall survival rates due to deaths from heart disease.

Event-Free Survival

Event-free survival refers to the percent of people who survive without a particular complication over a period of time. For example, this term could represent the number of people who did not develop neurological symptoms or bone pain due to the spread of a lung cancer to the brain or the bones.

Limitations of Statistics and Survival Rates

Keep in mind that survival rates are based on statistics and look at the population as a whole.

Statistics Don't Account for Variations in People or Tumors

Your prognosis may be different based on many variables such as your general health, and new treatments that have become available. Statistics also often group subtypes of cancer together. For example, even though the prognosis of lung cancers that are EGFR positive differ from those that due not have targetable mutations, the survival rates of both would be quoted as being the same.

Statistics are Dated

By the time survival rates are published, the statistics are frequently several years old. For example, when reporting the average 5-year survival rate for a type and stage of cancer, statistics are looking at people who were diagnosed at least 5 years before the study results were reported. With advances in the treatment of even advanced cancers, these numbers may not take into account changes in current treatment recommendations, and your own expected survival rate could be considerably higher. For example, most of the targeted therapies and immunotherapy drugs now available for lung cancer were not available when current statistics were recorded (in 2019 these numbers represent survival rates between 2010 and 2014).

If you've been recently diagnosed with cancer, keep in mind that there are many reasons to feel hope.

Lung Cancer Survival Rates by Type and Stage

This article lists survival based on different types and stages of lung cancer. Note that even within the same type and stage, cancers are all different and all have different molecular profiles. These are further broken down into:

Statistics

Keep in mind that survival rates are based on statistics and look at the population as a whole. Your prognosis may be different based on many variables such as your general health, and new treatments that have become available. By the time survival rates are published, the statistics are frequently several years old. For example, when reporting the average 5-year survival rate for a type and stage of cancer, statistics are looking at people who were diagnosed at least 5 years before the study results were reported. With advances in the treatment of even advanced cancers, these numbers may not take into account changes in current treatment recommendations, and your own expected survival rate could be considerably higher.

With regard to lung cancer, it is even more important to consider that survival rates may not reflect your outcome from the disease. There have been many recent advances in treatment, and an example may help explain this much better. Between 2011 and 2015 there were more new treatments approved for lung cancer — even advanced lung cancer —​ that had been approved in the 40 year period prior to 2011. In 2016, there are more new drugs being tested in clinical trials for lung cancer than for any other type of cancer. If you've been recently diagnosed with lung cancer, keep in mind that there are many reasons to feel hope.

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  • American Cancer Society. Non-Small Cell Lung Cancer Survival Rates by Stage. Updated 10/01/19.