Why Are Primary And Secondary Cancers Treated Differently?

Everyone who is diagnosed with cancer will often receive tailored, bespoke care, either in terms of the schedule of treatment they receive, whether they travel to another country to receive specialist care that may not be available in their country of residence, or if they need to look into more experimental treatments.

As a specialist radiotherapy centre, we understand that effective cancer care involves a wide, multidisciplinary approach that takes into account not only the primary specialist treatment, but also physical health, mental health, nutrition, occupational therapy and many other fields.

Everyone takes a different cancer care journey, not only because there are so many different types of cancers, but also because they can also affect the body in different ways.

One element that can have a major effect on cancer treatment is the stage and grade of the cancer, as well as whether it is a primary or secondary cancer.

To explain why this distinction is important for cancer treatment, it is important to briefly explain the difference between primary and secondary cancers.

How Do Primary And Secondary Cancers Differ?

Most cancers that are diagnosed are primary cancers, which are tumours, lesions or growths that develop in one part of the body and remain there until they are treated and destroyed.

In some cases, however, cancer cells can spread to another part of the body through the bloodstream or lymphatic system. Sometimes these cells just travel and are broken down, but in other cases, they can develop and grow in a new location.

This is known as metastasis, and the cancer that develops from this is a secondary or metastatic cancer.

Many, if not most, types of cancer have the potential to metastasise if they progress for long enough, and one of the reasons why early detection of cancer can be so important is to avoid metastasis if at all possible.

A secondary cancer will be described and diagnosed based on its original location. For example, prostate cancer that has spread to the liver is not described as liver cancer but as prostate cancer that has spread to the liver or liver metastases.

Can You Have A Secondary Cancer Without A Primary Cancer?

Whilst in most cases a person will have both a primary and secondary cancer, there are some relatively rare cases where a secondary cancer tumour is found but a primary one is not.

In some cases, this is due to previous treatment that has destroyed the primary cancer, but some cells have escaped into the bloodstream, whilst in other cases, the original cancer is so small and harmless that it has escaped detection but led to the development of a secondary tumour.

It is possible that the metastatic cancer is found before the original tumour, and a major part of treatment in this case is determining the point of origin, as it can have a significant effect on treatment.

In the example above, prostate cancer that has spread to the liver is not the same as liver cancer, and would require a very different set of treatments.

Are Secondary Cancers The Same As Advanced Cancers?

Secondary cancers are also known as metastatic, Stage 4 or advanced cancers, and whilst there is a considerable amount of overlap, not all advanced cancers spread, and not all cancers that spread are necessarily advanced.

This distinction is important, as advanced cancers often require more complex, specialist and immediate treatment to control and remove before they stop responding to treatment, which can require some significant decisions to be made when it comes to where and how you receive care.

Several cancers that metastasise can be cured entirely, most notably testicular cancer, whilst others can still be controlled very well depending on where they are located and whether they respond well to treatment.

This is one reason why some oncologists will use a different or more nuanced staging and categorisation system than the traditional four stages.

Systems such as TNM (Tumour, Node, Metastasis) are preferred as they can provide more accurate information in more complex cases, such as smaller secondary cancers that can be easily treated.

Whilst the example of testicular cancer that spreads to a part of the body where it can be treated easily without any major complications would still be considered a Stage 4 cancer, the TNM system would focus on its size, appearance in the lymph nodes (a sign of spreading) and metastasis.

In any case, oncologists will carefully consider your particular situation, overall health and tumour placements before arranging any specialist treatment.