Asking for my brother in law. Three brain mets treated with Gamma Knife in the spring, and now a new one on the scan. Can they just do it again?

Different situation from my acoustic neuroma, so I am out of my depth here. My brother in law has lung cancer that spread to the brain. Three small spots were treated with Gamma Knife in March and his follow-up scans since have been good, the treated ones shrinking. This week's scan shows a new small one somewhere else, and my sister is in pieces because she thinks this means the treatment failed.

They have an appointment next week. What I would like to understand before then: is a new one the same as the old ones coming back? Can Gamma Knife treat a new one, or do you only get one go? And someone mentioned whole brain radiotherapy to her, which sounds a lot more drastic. Is that what happens next?

Not mets, but I can tell you that the "you only get one go" idea is wrong in my case at least. Mine is a different condition but repeat treatment was on my consent form from the start.

Mark, I am sorry your sister is going through this. I cannot speak to his scans or his cancer, which his team will weigh with all the information, but I can explain the general picture, because these are good questions to take into the appointment.

A new metastasis in a different place is not the same thing as the treated ones failing. Radiosurgery treats the targets it is aimed at; it does nothing to prevent new ones appearing elsewhere, which is one of the reasons these patients have regular scans. If his treated spots are shrinking, the treatment did its job on them.

New metastases can often be treated with further radiosurgery, and it is not limited to one go. Teams decide based on how many new ones there are, their size and position, the dose already given to nearby brain, how the cancer is behaving in the rest of the body, and how he is in himself. Radiosurgery alone is generally preferred for small numbers of metastases, and modern practice increasingly looks at total tumour volume rather than a simple count. Whole brain radiotherapy is one of the options teams weigh, particularly when there are many new spots, and it can affect memory and thinking, which is why focused treatment is often preferred when it is possible. Ruth has set out how teams weigh treating again in repeat Gamma Knife treatment, and the comparison is in Gamma Knife versus whole brain radiotherapy.

Questions worth taking: is this a new spot or a treated one changing, how many are there now, what are the options and what does each mean for day to day life, and how often will he be scanned from here.

Passed this on word for word. My sister says it is the first time in a week she has felt like she understood anything.

Sending them both good thoughts. The not knowing before an appointment is the worst part of all of this.

Update. The team confirmed it is a new single small spot and the old three are still shrinking. They are treating it with Gamma Knife again next month, same unit, and nobody mentioned whole brain for now. My sister asked all the questions on the list. Thank you Edward.