Tag Archives: #varian

A tale of cancer and genetics: part 3 of 4

Summary: My wife had breast cancer. These posts describe: 1) finding out, 2) genetic testing, 3) radiation therapy, and 4) an incidental finding in the APC gene.

Radiation therapy

Kimberly’s radiation therapy tech Hannah standing in front of a Varian linear accelerator.

One month after surgery, Kimberly began radiation therapy, which is designed to reduce the recurrence of breast cancer after surgery by more than half. We met with a radiation oncologist and developed a 15-visit treatment plan. The cost of Kimberly’s radiation therapy was about $25,000, and fortunately our health insurance covered about 90%.

Radiation therapy and genetics have a curious relationship. The basic idea behind radiotherapy is to induce double-strand breaks in DNA with ionizing radiation. Although radiation damages both normal cells and cancer cells, most normal cells repair themselves, while cancer cells do not. Therapy is given in daily doses to allow the DNA in healthy cells to recover between visits.

External beam radiotherapy based on linear accelerators has been available since the early 1950s, and machines like the Varian Clinac above deliver a shaped beam of high-energy x-rays to a precisely targeted area. In Kimberly’s case, a surgeon had removed her tumor 1 month prior, so the target area was the breast where the surgery occurred–just in case a single errant cancer cell had wandered from the surgical site.

We made daily visits for several weeks and Kimberly tolerated the procedure well. On her right side she had what looked like a sunburn, a common side effect, that faded over the next month. We continued to have follow-up visits with both her medical and radiation oncologists.

A few days after finishing radiation therapy, we visited the Varian production plant in Palo Alto, California. It was fascinating to see the construction of these behemoth machines and learn more about their operation. (My favorite part was learning that the electron linear accelerator tube is tuned with a ball peen hammer.) As luck would have it, all of this activity occurred just 1 week before the COVID-19 shelter-in-place order hit the San Francisco Bay area in March 2020.

We spent the next 6 months not only sheltering-in-place, but also waiting for her follow-up mammogram to determine if radiation therapy was successful.

Interior view of the Varian Clinac linear accelerator. The cylindrical object on the left is a klystron tube, which was invented by the Varian brothers in 1937. The tube is the first part of a multi-stage process to create high-energy x-rays used in radiotherapy.