My lung cancer is ALK positive – what does that mean?
My lung cancer is ALK positive – what does that mean?
Conventionally, different types of lung cancer have been described according to their appearence when tumour cells are examined under a microscope (e.g. small cell or adenocarcinoma). However in today’s practice we also describe the different types of lung cancer based on the genetic changes that have occurred within them.
ALK positive lung cancer means the cancer started when a specific gene called “ALK” (which really has very little role in an adult human) gets turned on and starts shouting orders to drive a cell into becoming a cancer (i.e. to continuously divide and replicate). In the cancer cell, the ALK gene is turned on when part of it becomes rearranged (technically, the non-functional end of the ALK gene is replaced with the functional end of another gene, also known as a partner fusion gene). We can test for a number of partner fusion genes (e.g. EML4-ALK), but sometimes none are shown and your cancer might simply be called “ALK positive”.
If your cancer has not spread too far (localized disease) and the doctors are considering surgery, the ALK positive nature of the cancer currently would not influence treatment very much, although there are current trials that are evaluating ALK treatment after successful surgery. If your cancer had spread (regional disease) and chemotherapy and radiation were being offered, knowing you were ALK positive could influence the choice of chemotherapy used (e.g. pemetrexed has very good results in ALK positive lung cancer). In general ALK positivity doesn’t change the plan for these earlier stage situations, sometimes ALK testing is not even done at all (unless the cancer comes back) whilst other centers perform routine testing so the information is in hand if the cancer ever comes back.
If your cancer has spread far enough so that surgery or radiation therapy are unlikely to be the initial choice of treatment (distant disease), for those who are ALK positive, there are a range of pill options which would be very effective. Although not a cure, can control the disease in most people for several years. The most commonly used of these ‘ALK inhibitor’ pills are alectinib, brigatinib and lorlatinib. These pills also get into the brain and so, even if the cancer has spread to the brain, if the cancer is ALK positive, these pills can be used to shrink the cancer and avoid brain radiation.
Often the cancer ‘gets wise’ to the ALK inhibitor and begins to grow again after initially responding. That can be growth in the body or in the brain, and it can be one or many different sites of disease. The good news is that at that point there are still options to consider – sometimes the pill continues and a few, small growing areas are treated with radiation; sometimes the growing area is sampled (re-biopsied) and the cancer reanalyzed for new pills or a different ALK inhibitor pill is tried without a biopsy. If the pills alone cannot control the cancer, sometimes chemotherapy is recommended (e.g. pemetrexed). One of the current debates is the value of continuing the ALK inhibitor with chemotherapy if you ever get to that point (although access to the combination of drugs varies across different healthcare systems in the world).
Whichever treatment you are advised to have, support is available though the ALK positive patient community such as “ALK Positive Patient Group” and there are multiple national and international resources and medical opinion options to help you understand the different treatments.
The author of the article Professor Ross Camidge has received funding from Pfizer, Roche/Genentech (that makes alectinib) and Takeda (that makes brigatinib).
Updated 2 March 2022 after patient review and suggestions.