Is radiation therapy recommended after surgery?

Sometimes. Depending on the type of tumor, extent of disease involvement, surgical margins, etc. Radiation can be used early as planned course or used later as salvage.
It depends. It depends on the type of cancer, stage of disease, and the result of surgery. There is no one answer for this question.

Related Questions

Which radiation therapy do you recommend and why? Tomotherapy or rapidarc.

Both. Its like recommending sony versus samsung. Each device is from a different manufacturer that can accomplish the same thing. A doctor may say theirs is better but if he had the other device he would be saying the same thing. Its more important to know your doctor has the knowledge to treat a disease and a good reputation.
Either. Both of this technologies do essentially the same thing. Although these two machines look different, their ability to accurately and rapidly treat most cancers will not be different. Don't fall for the marketing hype.

Why would my doctor not recommend radiation therapy after a lumpectomy?

Low risk to recurr. There is a good chance the type of disease was dcis (ductal carcinoma in situ). This is a pre-invasive disease (not cancer yet). Radiation can be avoided in the most favorable group of patients with dcis since chance of recurrence is very low. Typical conditions met are: 1) large clear margins of resection was obtained, 2) the disease is not too large (size), 3)not too aggressive (low-grade).
Ask your doctor why? This depends on your condition and age. Assuming you have cancer of the breast there are some (by no means all) radiation doctors who may not recommend it if it is early stage and you are over 70 and have good receptors (er and pr) so that you can take a hormone. Best bet is to get a second opinion and likely they won't agree.
It's the right thing. In 1970, no one had lumpectomy (partial mastectomy) and everyone had "radical mastectomy. Today many womaen can avoid mastectomy. The standard is to get roughly 5 weeks of adjuvant radiotherapy to the involved breast. Why because studies proved that no radiotherapy resulted in breast relapse and breast loss. Some women are now choosing to have both breasts removed.
??? You need an opinion from a radiation oncologist so you can adequately understand why you do or don't need treatment. Unless that recommendation was made by someone who specializes in radiation treatments I would hesitate to accept it.
Lumpectomy radiation. Almost all patients who have a lumpectomy need radiation afterwards because of the risk of residual microscopic cancer. A couple of exceptions are in situ cancer that is very small, low grade, and widely clear margins; or invasive cancer that is very small, er +, age over 70, and margins over 2 mm.

Does drinking more water support the removal of necrotic brain tissue? I'm receiving radiation therapy to treat a brain tumor. A nurse recommended drinking lots of water to help my body remove necrotic tissue. I've been checking for information on the web

Breakdown. Breakdown products of tumor therapy can, in some cases, cause an injury to the kidneys. Staying well hydrated can reduce this risk. This problem is more likely with very large tumors, which you probably do not have, but it's an easy and inexpensive precaution, so probably worth incorporating into your regimen.
Hydration is good. This keeps your kidneys flushing out toxins and metabolites.
No. It does not remove any brain tissue. But drink water normally. Excessive water drinking may cause low sodium and may cause ur brain to swell and in extreme condition u may pass out. L. only listen to ur md.