Chemotherapy before surgery reduces bowel cancer – 03/16/2023 – Health
A new procedure in the treatment of advanced colorectal cancer reduced the recurrence of the disease in patients by 28%, showed a study published in the Journal of Clinical Oncology.
Instead of traditional post-surgical rounds of chemotherapy, the study included six weeks of chemo before the patient underwent surgery, plus 18 weeks of treatment after surgery. The results show that the technique can help reduce the size and stage of the tumor, facilitating its surgical removal, in addition to reducing the risk of tumor cell shedding during surgery, reducing the chance of metastasis.
The Inca (National Cancer Institute) estimates that in 2023 there will be 45,630 new cases of bowel cancer in Brazil, 23,660 in women and 21,970 in men.
Colorectal cancer is the third most diagnosed cancer in the world and has appeared in the media because of recent cases among celebrities, such as former soccer players Pelé and Roberto Dinamite and cartoonist Paulo Caruso, who died from the disease. It is the third most common cancer among men, after prostate and lung cancer.
Among women, bowel cancer ranks second in incidence, behind breast cancer. Singer Preta Gil recently announced that she was diagnosed with this type of cancer and is undergoing treatment.
The new procedure represents a paradigm shift in the treatment of bowel cancer, especially in the more advanced cases of the disease, says surgeon Rodrigo Oliva Perez, coordinator of the Coloproctology and Intestines Nucleus at the Specialized Center for Digestive Apparatus at Hospital Alemão Oswaldo Cruz, in São Paulo.
“In colon cancer, this is the first time that there has been a change in the order of treatment”, says Perez. “For patients who have clearly advanced tumors, we can use this procedure quite safely. In obvious cases, it changes the paradigm. A significant percentage will change the treatment.”
The surgeon, however, criticizes the study. The first is that the final result of the procedure took eight years to be disclosed, since the researchers were looking for the most positive result possible.
“A series of revisions and statistical modifications were made, because the authors were interested in the result being positive. The study is giving positive results in two years [de tratamento]. We usually use treatments in three or five years, two years is a little different from what we are used to”, says Perez.
He claims that, because of the delay in disclosing the results, the study lagged behind new techniques that emerged in the period, such as research on circulating tumor DNA, which detects cancer in the blood and is an important tool for defining the use of post-surgical chemotherapy.
The doctor also pointed out that chemotherapy was given for 24 weeks after surgery, whereas currently the standard is 12 weeks —24 sessions would only be indicated for a minority.
In addition, according to the doctor, 25% of the control group normally do not need to undergo chemotherapy after the operation —because they are not very serious cases or because the tumor has shrunk, for example. In the study, however, all 354 patients in this group received 24 weeks of postoperative chemotherapy. “That means these patients must have had unnecessary treatment.”
Another criticism made by the surgeon at Oswaldo Cruz concerns the use of computed tomography to stage the tumor —that is, analyzing the growth rate and extent of the disease, in addition to determining the type of tumor and its relationship with the host. The ideal, he says, would be high-resolution magnetic resonance imaging, which gives more detail and sharpness to the images.
“Tomography has limitations, and they end up being wrong in 20% to 25% of cases. Nowadays we perform the surgery based on the biopsy result, so we know when there is benefit or not from the treatment.”
In colon cancer, this is the first time that there has been a change in the order of treatment. For patients who have clearly advanced tumors, we can use this procedure quite safely. In obvious cases, it changes the paradigm. A significant percentage will change treatment
Perez’s concern is followed by oncologist and oncogeneticist Isabella Tavares, from the Center of Excellence in Oncology in Maringá (PR), who recognizes the importance of the study, but also makes reservations, mainly regarding neoadjuvant chemotherapy (before surgery).
“Toxic side effects can make the patient unfit for surgery. Another possibility is to cause progression of chemoresistant tumors”, he says. “It’s important that more research is done to determine long-term outcomes after neoadjuvant chemotherapy.”
To compare the effectiveness of this chemotherapy with standard adjuvant, the researchers assessed residual or recurrent disease during the two-year follow-up period after surgery.
The survey was conducted from May 2008 to December 2016 by FoxTrot, a collaborative group funded by Cancer Research UK, with 1053 patients from 85 clinics: 79 in the UK (949 patients), three in Denmark (88) and three in in Sweden (16).
The last phase consisted of 699 patients with advanced colorectal cancer whose tumors had not metastasized. This included patients whose cancer had grown into or through the outermost layer of the colon or rectum wall but had not spread to distant tissues.
As a result, chemo before surgery led to significant tumor regression and was associated with side effects similar to those normally seen after adjuvant chemotherapy.
The study found that this approach (neoadjuvant chemotherapy) was safe and more effective, reducing tumor size or spread and preventing disease recurrence more than with standard adjuvant chemotherapy.
Most common symptoms of bowel cancer
- Blood in the stool;
- Change in bowel habits (alternating diarrhea and constipation);
- Abdominal pain or discomfort;
- Weakness and anemia;
- Weight loss without apparent cause;
- Change in the shape of the stools (very thin and long stools);
- Abdominal mass (tumor).
These symptoms are also present in cases of hemorrhoids, worms, gastric ulcers and others, and must be investigated for a correct diagnosis and specific treatment. Most of the time these symptoms are not caused by cancer, but it is important that they are reported to the doctor, especially if they do not improve in a few days.
Source: Ministry of Health