Recurrence of Cancer Post Radiation Therapy
By Dr. Tejinder Kataria,
Recurrence of cancer is cancer cells coming back after completion of cancer directed treatment. This can happen after 3 months to 20 years for various cancers as cancer is not one disease. The different tissues in the body have different potential to form cancers and the malignant potential of each is different. Cancers like brain tumors remain localized to the brain and very rarely travel to other parts of the body except the spine. Prostate cancer is slow growing and may take many years to manifest its symptoms. Cancers of the oral cavity and head & neck area are relatively fast growing but remain loco-regional in 90% of the patients. However, breast cancer is considered local/loco-regional as well as has potential for distant metastases even after 10 years of primary surgery.
Recurrence can be (i) Local – in the area where treatment was given for the first time. (ii) Loco-regional- close to the area of first cancer. (iii) Distant or metastatic-away from the first cancer site.
Radiation is recommended as a single modality treatment or in combination with surgery &/or chemo/immunotherapy for cancer management. Surgery and Radiation are local or loco-regional treatments whereas chemotherapy is required for controlling or preventing distant metastases. The recurrence rates vary depending upon the stage and type of cancer.
For head & neck cancers, radiation therapy provides > 95 % chances of cure for stage I – larynx cancer. Interpreted for recurrence it means a 5% chance of cancer coming back in, the lifetime of, treated patients. Similarly, breast cancer stage I cancer treated with surgery alone chances of local recurrence are 25-30% but addition of radiation reduces the recurrence rates to less than 3-5%.cancer uterus stage I , post surgery is curable in 95% of patients with >50% requiring local radiation after operation.
A recurrence after radiation therapy can be managed by surgery, chemotherapy, targeted therapy, immune-therapy or re- irradiation.
Re irradiation after local or distance recurrence, is possible after 12 months of the first course of radiotherapy. The doctors map the area treated earlier and calculate the decay of dose as well as determine the tolerance dose of the surrounding normal tissues before deciding the modality and dose of radiation second time.
Recent studies over the last decade have shown that re-radiation with stereotactic body radiotherapy (SBRT) is effective in 50-70% of patients for long term control of oligometastatic or small volume recurrence. Special techniques including Robotic RadioSurgery developed by Stanford University, in late 1990s is very useful for patients requiring e-irradiation for local/loco-regional or distant metastases to lungs, liver, bone, brain or lymph nodes.
(The author is Chairperson Radiation Oncology, Cancer Institute Medanta – The Medicity. The article is for informational purposes only. Please consult health experts and medical professionals before starting any therapy or medication. Views expressed are personal and do not reflect the official position or policy of the Financial Express Online.)
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