Rectal Cancer 101: Workup, staging, and treatment 得了直腸癌，該怎麼辦？

Added: 2026-05-22

[00:00:05]Hello everybody, my name is Ronan Shay and welcome to my channel. I'm a GI oncologist practicing in Seattle. I'm a member of the GI task force at National Cancer Institute. uh I have been treating hundreds and hundreds of the GI cancer patient and when I talk to my patient they always like to record what I'm saying and they ask me to repeat the information uh in the subsequent visits.

[00:00:31]I've been thinking why don't I record videos uh to share my knowledge with my patients so that they can uh watch all this videos at their home. I think that's a good idea. So I bought a new set of camera. I bought a new set of the microphone and today I'm going to share my first video. I've been thinking about what's my first video will be. Um but I think I'm going to pick rectal cancer because this is one of the most complicated uh treatment regimen uh among all cancers. So let's talk about what's rectile cancer. Okay. Colorectal cancer is one of the most common cancer.

[00:01:08]The unique thing about rectum is that because it's so close to the outside world, uh we can consider radiation. So that's number one difference about rectum. You can consider radiation for rectal cancer. Number two is that rectum has lots of muscles and those muscle uh is trying to prevent stool from coming out of your body. So without those muscle people could have bow incontinence. That is why we always try to prevent surgery if we can do that. So that's the overview about how we treat rectal cancer. Let's talk about the details. Okay. When we talk about rectal cancer, we usually refer to adino carcinoma. Adocarcinoma is the most common type of cancer in rectum. What is recttoarcinoma?

[00:02:03]Well, adocarcinoma is a Latin word.

[00:02:05]Adinome means gland. Carcinoma means cancer. So adinocarcinoma basically is the Latin word for cancer of the gland in the intestine. Okay. So that's why it's the most common type of a cancer in rectum because our bowel has lots of glands to release digestive fluid. All right. So how do we treat rectal adinino carcinoma?

[00:02:31]The first thing we know is what is the staging? Okay, the staging basically is how invasive a cancer has become.

[00:02:42]The way we define staging is we order a CT whole body scan and also MRI of the pelvis. Dcton is a very delicate area.

[00:02:52]It has a lots of vessel, a lots of nerves there. So we want to clarify the stage of the disease. we need the MRI because it's more fine-tuned for a complex area like uh the pelvis.

[00:03:07]All right. Once we get a CT scan MRI, then the first thing we want to see is has this cancer spread to anywhere else.

[00:03:16]For example, liver, lung, paronium.

[00:03:18]These three places are the most common uh places of spreading uh from a rectum.

[00:03:24]If the cancer has spread to somewhere else, uh this is classified as a stage four disease. Uh for stage four disease, we don't usually consider radiation or surgery out front. We treat the disease with chemotherapy. Why is that? Because when a disease is already spreading outside of the original organ, which is rectum, that means it is circulating in the systemic blood flow or lymphatic duct. So we need to use chemotherapy to reduce the systemic spreading what we call tumor burden before we even consider something locally. If we do it's the reverse way we could risk basically disease coming back quickly right after surgery. Now let's say if the cancer has not spread to somewhere else this is not a stage four disease.

[00:04:13]What do we do next? Well, we also need to ask a surgeon to see how deep the tumor invades. Okay, if the surgeon and MRI says, hey, this tumor only invade the superficial layer. It doesn't invade the muscle layer of the rectum, then this is stage one cancer. Stage one cancer, we do surgery to remove it. As long as the surgery doesn't jeopardize the muscle that's holding the stool. If the surgery jeopardize the muscle, then we need to consider radiation first to shrink the cancer. All right. So basically now repeat stage one we do surgery and call it a day. Stage four we do chemotherapy and uh hopefully we can reduce the systemic spreading of the cancer. Now the interesting part is a stage two and three. Stage two basically means the cancer invades the muscle.

[00:05:04]Okay. Uh but does not invade the lymph node. Stage three means the cancer has invaded lymph node. Why lymph node invasion is so important for us to assess before we start treatment? Well, cancer likes to spread right before cancer spread to somewhere farther like lung or liver. They like to spread to somewhere closer like a lymph node. The lymph is right outside of your bowel.

[00:05:31]It's like immune fortress. So whenever we see a lymph node that's getting large that means immune system is fighting very hard for you. uh that also increases the risk of this cancer already spreading somewhere else. That is why stage three cancer has a higher risk of recurrence compared to stage two or one because the lymph node is already involved. The cancer is already trying to spread even if it hasn't shown up on the imaging as a stage four disease. So for stage two and three disease most of the times we treat patient with radiation and chemotherapy.

[00:06:09]Why do we do radiation? Well, radiation is to try to shrink the cancer and hopefully we can get rid of the cancer.

[00:06:17]Uh and radiation can also radiate those lymph node that's outside rectum where it might be difficult for surgery to reach.

[00:06:25]The purpose of chemotherapy is to try to reduce uh or eliminate all the cancer that could have escaped from the rectum.

[00:06:35]Statistically speaking, stage two and three cancer have a higher risk of recurrence because the cancer might have spread outside of the rectum. That is why we will want to do chemotherapy to try to reduce the chance of the spreading. Okay. So for stage two and three disease, we do both radiation chemotherapy.

[00:06:55]How do we do that? based on a study called OPRA and also some previous study for example prodig study, rapido study, AIO 94 study. The current stand of care is we do radiation first and after that we do chemotherapy. When we do radiation, we also give them a smaller dose of chemotherapy and I will talk about why we do that in a second. The radiation is a daily radiation usually on weekdays and that's usually for five to six weeks depending on the size of a tumor. The radiation doctor will decide how many days of radiation you will need and we usually add a chemotherapy pills that's called capecabine. The pills is given twice a day only on radiation days which means on weekend there's usually no radiation so you don't take the capein pills. The reason we give the chemo pills with the radiation is because every time cancer get radiation they will want to repair the broken DNA.

[00:07:56]Chemotherapy is like a fake DNA. So it's almost like we are trying to trick the cancer to build a skyscraper with hundreds of sandbags. Okay, fake DNA. So when the cancer take that fake DNA, they will crumble. they are not able to repair themselves and they will die eventually. So that is uh the purpose of the chemotherapy and radiation together what we call concurrent chemo radiation and that's for five to six weeks and then after that five to six weeks of a concurrent chemo radiation we will enter 3 to four months of pure higher dose chemotherapy. Remember this phase is to eliminate a cancer that has spread outside of a uh a tumor which you may not be visible on the imagining but we know statistically speaking stage two and three disease have a higher risk of recurrence. So we want to give you higher dose of chemotherapy to eliminate the risk of recurrence. The way we treat people at this phase is we give them capecabine and oxy platinum. Capsitabine is the same pills you took when you got chemo radiation. Okay? So that's a twice daily pills but because you are no longer getting radiation. So this capsitin pills you take it for two weeks and then you break for a week and then repeat. So two week on one week off regimen. Oxyoplatin is a IV treatment that you get for every 3 weeks. Okay?

[00:09:25]And you do that for four to five rounds.

[00:09:28]Basically three to four months. Why is there a difference between four uh three and four months? Because one study did three months, the other side did four months. Either way, if you tolerate well, I say four months. If you don't talk very well, I say three months or even less. All right. People ask me, "What's the chance of me getting rid of this cancer with just chemotherapy and radiation?" 54%.

[00:09:52]54% based on OPRA study. Some patient they still have resided disease. So even after all this chemotherapy and radiation, you still need to get surgery. So in total 80% chance of a cure with or without surgery. 80% chance of a cure. When I say cure that means fiveyear uh no disease recurrence because at five years we release you from clinic. We we call it a cure.

[00:10:18]All right. So in summary the way we treat this rectal adinocarcinoma based on staging is stage one we do surgery if this is feasible. Stage four we give uh uh chemotherapy. Stage two and three we give cheo radiation followed by chemotherapy.

[00:10:38]Finally there's a rare type of the rectal cancer uh which carries a mutation called deficient mismatch repair. That cancer will be very sensitive to imunotherapy. I will record another videos to talk about how we treat rectal cancer with deficient mismatch repair. Um okay and at the end of this talk I also want to say this is only for educational purposes. If you um uh listens to all my uh talk today, thank you for listening. But I also want to let you know that uh in the real world uh it's not like a textbook. Okay.

[00:11:14]It's usually requires multiddisiplinary discussion among radiation oncologist, medical oncologist and surgeon to discuss in a meeting to design a best plan for you. So there are lots of variety of these cases of rectal cancer that could be what I'm talking about today is the majority of cases will be treated in this way. Stage one surgery, stage four chemo. Stage two and three you do chemo radiation first followed by chemotherapy. All right. Thank you for listening to my first ever videos. I hope this is helpful. Um and if you're my patient, I will see you in clinic and feel free to ask me question. Bye.