Uses of chemotherapy. For mesotheliomas that can be treated with surgery, chemo may be given before surgery to try to shrink the cancer and lower the risk of spread. This is called neoadjuvant therapy. Chemo can also be given after surgery to try to kill any cancer cells that were left behind.or cancers that canât be removed with surgery, chemo may be the main treatment (alone or along with radiation therapy). Chemo may shrink the cancer or slow its growth, but it is very unlikely to make it go away completely.