I’VE ALWAYS WONDERED …
by EMMA SECOMB

Welcome to our new Q&A column I’ve Always Wondered… for all the big and little medical questions you’ve always wanted to ask. 

I’m a breast and endocrine surgeon but over the years I’ve become allergic to gloves and skin preps (and a few people), so I’ve recently retired from surgical practice on the Sunshine Coast. Medical communication has always been my passion and although I’ve loved operating it has always been the process of sharing information and developing understanding with my patients that has kept me engaged. 

Each edition I’ll choose a question sent in by readers to explore more deeply. As this is the first edition I’ve chosen one of the questions I’ve been asked most often.

I’ve always wondered, what is cancer actually?

Cancer, like all the words that mean so much in life, is surprisingly hard to define. I think the most useful starting point is to understand cancer in terms of two fundamental processes: unregulated cell copying and loss of cellular markers of identity. 

The four trillion or so cells in our bodies are highly specialised and form intricate networks to create our tissues and organs. They need to be replaced continually throughout our lives and faithful copies need to be made – the right cell type, at the right time, the right number of copies. In broad terms this process is dictated by our DNA and damage to the one or more of the many genes regulating cell copying may lead to too many copies, copies with errors that predispose to more errors and copies of immature and incomplete cell types. What arises in the body is a “lump” made by these extra cells. This lump can be the ‘canary in the coal mine’ that leads to diagnosis, or can itself cause serious harm if it blocks a critical function as it expands.

The other hallmark of cancer as a process is loss of cellular identity. A nerve cell with its long tentacles carrying electrical impulses and endings capable of transmitting those signals via chemical release is vastly different to a breast milk duct lining cell that forms a smooth tiled passage and tight barrier between the internal and external environments. Cancerous cells are often incomplete or immature versions of the cell they are meant to be. As a result, they lose their tight relationship to neighbouring cells and can drift or move through tissues, blood, lymph or membranous body cavities in ways a mature fully developed cell can’t. This is what underpins movement of cancer from where it began (the primary cancer) to movement to other sites in the body (secondary cancer, or metastasis). Vital organs and processes can be overrun by invasive cancer cells, and loss of critical functions in these organs can lead to death from cancer.

So although we naturally tend to think of cancer in terms of the organ it appeared in (breast cancer, bowel cancer, skin cancer and so on) it’s the underlying loss of regulation of cell copying and markers of cell identity that underpin all cancerous processes. There are shared processes at a molecular level that cross between cancers arising in very different organs – and research breakthroughs in one type of cancer often translate into insights and treatment advances in other cancers. Moving our focal point from the visible lump to these cellular and molecular changes is the paradigm shift that has seen cancer move from a universally fatal disease 100 years ago to one that is now often curable when caught early enough in its development.

I hope this has been helpful and interesting. 

Email your questions for Emma to editor@sunnycoastmedia.com.au.

 

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