Solitary Pulmonary Nodule

[Willy]

hi guys,
i want to ask your opinion, my father in law did a PET scan ,and the result was 5.5 mm diameter nodule in the left lung,then after 3 month the nodule increased to 8.6mm
From what i read on the article,if the nodule size is below 3cm, then it is not cancer.

and my point is..if this things not a cancer,does it okay to leave the nodule like that? do we have to
get rid off the nodule by taking surgery ,chemotherapy.etc...though the nodule is not a cancer and do nothing with our health

Please need your help with this,
thanx