Could radiation therapy help me live my last few months with less cancer pain?

Yes. Many cancer patients that can not be cured may have pain or other symptoms. These problems can be helped by palliative radiation which is shorter and quicker.
Yes. Yes, fortunately radiation has a good palliative role for pain palliation. Usually, 70% of the patients achieve some level of palliation.
Palliative care. Interating radiothrapy into palliative care and hospice programs results in a focus on doing everything necessary to help provide comfort and maintain function. Also, many times, just a single radiotherapy dose can help deliver relief of pain. Team work and acceptance of the move to "let's focus on quality and comfort" rather than "do anything" regardless of low liklihood helps.

Related Questions

How long is it supposed to it take before radiation therapy starts to reduce colon cancer pain?

Few weeks to month. It can take few weeks to c results but can take l.
Depends on where. If there is pain caused by the cancer spreading to a bone or other organ, radiation therapy can work as quickly as in a few hours. To relieve pain. Depending upon how much radiation is given per treatment and how many treatments are required, the pain and tumor can shrink slower or more quickly. The more radiation per treatment the more dramatic and quick effect on tumor as well as normal cells.