Why is resection of tumor not done in metastatic disease?

[sameeralord]

Hello everyone,

Let's take a woman with a breast lump for example and it is malignant. I know that stage 3 and 4 disease, eg advanced/metastatic disease treatment is chemotherapy/radiotherapy. Then after it is downgraded they surgically resect the lump (stage 1 and 2). While this makes sense my question is why don't they still remove the lump in advanced disease and then give chemotherapy/radiotherapy. Reason been if the tumour is not resected and you give chemotherapy, since the primary tumour is still there it would keep producing metastasis. Is the reason that surgical resection is too dangerous when metastasis present. Why is that? Thanks

 

[Choppy]

If you're talking specifically about breast cancer, first, it's important to understand that it's classified by a TNM system. T refers to the primary tumour size. N refers to involvement of the lymph nodes, and M refers to the presence or absence of metastasis. If the cancer has metastasized, then it classified as stage 4.

Once the cancer has metastasized the focus in treatment shifts from curative to palliative. At stage 4, the 5 year survival rate depends on the location of the metastasis, but is around 22%, compared to about 72% for stage 3 and higher for the earlier stages.

Surgical resection of the primary disease can still be offered in stage 4, but tends not to be. One issue is that once the cancer has metastasized, from breast it tends to move to sites like the lungs, liver or in more rare cases the brain. It can also cause some very painful bone metastases. In these situations treatment of the secondary site will often take precedence both in terms of overall survival and quality of life. There may also be issues of how well the patient might tolerate and recover from a major surgery, particularly in the context of the rest of the disease. On top of that, surgical resection of the primary site is not going to prevent additional metastases anyway because at that stage the cancer is in the lymph nodes and wherever else it has metastasized to. What surgeons will look at though is whether there is any evidence that surgical resection will offer any advantage to the patient in the particular case. In some situations it might and they should have that conversation.

 

[sameeralord]

Thanks for the reply Choppy. The only thing I didn't understand is

On top of that, surgical resection of the primary site is not going to prevent additional metastases anyway because at that stage the cancer is in the lymph nodes and wherever else it has metastasized

But since the primary tumour is still there, wouldn't it keep producing metastastasis even though we are removing them at the same time. Eg a water bucket, and some guy pouring a cup of water in (tumour) as another guy pour a cup out (chemotherapy), so there is no net gain and task is futile.

 

[Choppy]

It would.

But mets could also come from anywhere else the cancer has spread to as well. So you're likely right in that removing the primary tumour is likely to reduce, for example the number of circulating tumour cells, and therefore reduce the probability of inducing further metastases. But it's not going to drop it to zero, because now you have cancer in other regions to worry about and that can also metastasize, and all of those sites can be tricky to find. And with mets, you generally have higher priority concerns.

 

[sameeralord]

Thanks Choppy. Yeah I think the problem is as you have said even though resecting tumour would decrease the number of tumour cells, doing a surgery in a metastatic disease is risky as

1. Patient is not suitable to endure a major surgery when there is systemic metastasis, as his body would not be able to handle it.
2. Doing the surgery could accidentally create more pathways for metastasis to spread.
3. As you said systemic problems caused by metastasis takes precedence and must be treated first.

Am I right?

 

[Choppy]

Yes.

And as I said, it's not that this is never done. It's just not that common and probably not "standard of care."

You might be interested in this article that suggests surgical excision of the primary tumour may result in overall improved outcome:
http://link.springer.com.ezproxy.lib.ucalgary.ca/article/10.1245/ASO.2006.03.033#
You have to take it with a grain of saly though, because the study was done retrospectively comparing those who had surgery and those who did not. The fact of the matter is that those who had surgery may may been better off in the first place (which could have been why they went ahead with the surgery).

 

[sameeralord]

Yeah true. Thanks for the help