Most people with skin cancer receive between 5 and 30 radiation treatments, depending on the type of radiation, the size of the tumor, and where it’s located. A small basal cell carcinoma on the nose might need just 5 sessions over one week, while a larger or more aggressive squamous cell carcinoma could require 30 or more sessions spread over six weeks. There’s no single standard number, but the most commonly used schedules fall in the range of 5 to 20 treatments.
Common Treatment Schedules
Radiation for skin cancer follows a principle: the total dose of radiation is split into smaller portions called fractions, with one fraction delivered per session. Fewer sessions mean a higher dose each time, while more sessions use smaller doses. Both approaches can be effective, and the choice depends on your specific situation.
The National Comprehensive Cancer Network lists four standard schedules for early-stage tumors under 2 centimeters:
- 5 sessions over 1 week (higher dose per session)
- 15 sessions over 3 weeks
- 20 sessions over 4 weeks
- 32 sessions over about 6.5 weeks (lower dose per session)
A meta-analysis of skin cancer radiation outcomes found that three schedules in particular, ranging from 5 to 15 sessions, produced good cosmetic results in about 80% of patients. This has shifted practice toward shorter courses for many people, especially those with small tumors.
How Tumor Size and Type Affect the Number
For small tumors (2 centimeters or less), cure rates exceed 90% across a wide range of schedules, from as few as 5 sessions to as many as 25. The tumor’s size matters far more than the exact number of sessions when it comes to outcomes. Both basal cell carcinoma and squamous cell carcinoma of this size respond similarly well.
Larger tumors tell a different story. When a skin cancer is bigger than 2 centimeters, more sessions generally improve the odds of clearing it completely. A schedule of 15 sessions at a moderate dose controls a large basal cell carcinoma roughly 80% of the time, but extending to 20 or more sessions pushes that above 90%. The difference is even more dramatic for large squamous cell carcinomas: 15 sessions may control only about 46% of them, while 30 sessions brings control above 90%. This is why your doctor may recommend a longer course if your tumor is larger or more aggressive.
Superficial Radiation Therapy
Superficial radiation therapy, or SRT, is a newer option that can be done in a dermatologist’s office rather than a hospital radiation center. It uses low-energy radiation that penetrates only a few millimeters into the skin, making it well suited for cancers that haven’t grown deep.
Typical SRT schedules range from 7 to 30 sessions. A common protocol delivers 15 sessions over three weeks, with treatment five days a week. Some offices use a three-day-per-week schedule instead (such as Monday, Wednesday, Friday), which stretches the same number of sessions over a longer calendar period but can be easier to fit into daily life. Shorter courses of 7 sessions are also used, though they deliver a higher dose each time.
Electronic Brachytherapy
Electronic brachytherapy places a radiation source directly on the skin surface, concentrating the dose on the tumor while sparing surrounding tissue. The most common schedule is 8 sessions delivered twice a week over about 4 weeks. Treatment courses in published studies have ranged from 2 to 29 sessions, but 8 is the most frequently used number. The average treatment course wraps up in about 27 days.
Hypofractionated (Shorter) Courses
For elderly patients, people with mobility challenges, or those who simply can’t commit to weeks of daily appointments, hypofractionated schedules compress treatment into very few sessions. Some protocols use just 3 or 4 sessions, each delivering a large dose. One approach delivers 3 sessions of high-dose radiation, while another uses 4 sessions. Even a single high-dose session is sometimes used for select small tumors.
These ultra-short courses have shown effective tumor control for non-melanoma skin cancers, particularly on the face and in older patients. The trade-off is that higher doses per session can sometimes produce more noticeable long-term skin changes compared to a longer, gentler course.
Radiation After Surgery
When radiation is used after surgical removal of a skin cancer (because margins were close or the cancer had high-risk features), the number of sessions is typically higher. Guidelines recommend either 30 to 32 sessions over 6 to 7 weeks, or a slightly condensed course of about 25 sessions over 4 weeks. Post-surgical radiation aims to eliminate any microscopic cancer cells left behind, so the treatment area is often larger and the total dose higher than for a primary course.
What Each Session Looks Like
Individual sessions are quick. The radiation itself takes only a few minutes, but you should plan for about an hour per appointment. Most of that time goes to changing, positioning, and setup. A therapist will carefully align the radiation beam to the treatment area, often using marks on your skin or a custom mold to ensure precision. Once everything is in place, you won’t feel the radiation during delivery. There’s no pain during the session itself.
Most schedules run Monday through Friday when treatments are given daily. Some protocols, particularly SRT and brachytherapy, use a two or three times per week schedule instead. Your total calendar time in treatment could be as short as one week or as long as seven weeks.
Side Effects and Recovery Timeline
Radiation side effects are cumulative. Most people don’t notice skin changes until a few weeks in, roughly a quarter of the way through their course. The treated area typically becomes red, dry, or tender, similar to a sunburn. These reactions intensify as sessions continue and usually peak near the end of treatment or shortly after.
Mild radiation skin reactions start improving within a few weeks of your final session. Your skin may remain sensitive for up to a month after treatment ends. Shorter courses with higher doses per session tend to cause a more intense but briefer reaction, while longer courses with lower doses spread the effects out more gradually. Either way, the skin in the treated area may look slightly different in color or texture long-term, though this fades for most people over the following months.