Biopsy of nodule in the lung

How large does a nodule in the lung have to be for the doctor to do a biopsy?  At this time, the doctor feels my husband's colon cancer has metasatic into his lungs. Based on the CTscan, he has 49 nodules that are 1 mm and one that is 5 mm. The will not be able to confirm if it is cancer until they can do a biopsy. We have to wait another month and hope they will be able to do the biopsy. Could it be something else...like an infection or fungus?

[Kamal S Saini, MD, MRCP (UK), DM]

Hi,
There are many methods to determine if the lung nodules are cancerous or not.
One of the simple, non-invasive methods is the PET-CT scan. PET (positron emission tomography) uses a radio-active substance called FDG which is injected into the veins of the patient, to accurately identify areas of metastases.
I suggest that after quickly confirming the nature of these lung lesiona, appropriate therapy (including monoclonal antibodies against VEGF) be begun at the earliest.
All the Best, and God Bless!