What is Metastasis of Adenocarcinoma of the Lung?

I have a new metastasis to my left chest muscle. It has caused me much pain in the last two weeks from early May 2015.

This is an explanation of this metastasis ("spread of the cancer to a new site")  by my radiation oncologist son Kerwyn.
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Hi Dad

The tumour on your left chest wall is a metastasis from your lung cancer.

Cancers are classified in two ways:
(1) By the site of the Primary Tumour
(2) By the Histological type (cell of origin)

In your case, the cancer started in the lung. Hence you have a lung cancer. It is of glandular origin. Hence it is an adenocarcinoma.

Regardless of what places the cancer travels to (metastasises): bone, brain, pleura (lung lining), wherever: it will always be a lung adenocarcinoma. It so happens that the cancer has now traveled to the soft tissues (ie., muscle, fat, cartilage) of the left chest wall. It is still a lung adenocarcinoma. In jargon: metastatic lung adenocarcinoma to (brain/contralateral lung/bone/etc).

Some people do have two primary cancers. Most often these are separated in time (in jargon: metachronous). It would be rare for someone with an active metastatic malignancy to be diagnosed with a new primary cancer, as a further metastasis from the existing cancer is much more likely. In any event, soft tissue sarcomas are very rare primary cancers.

The only way to be sure (100%) is to biopsy. However, I think your doctors will go with the 99.5% certainty that this is your existing cancer as a biopsy would be quite painful. So the treatment offered (be it radiotherapy or a different chemotherapy) would be that for a metastatic lung cancer, not a new primary.

Hope this makes things clearer.

Kerwyn
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